MySQL Connector/J 6.0 Developer Guide

Abstract

This manual describes how to install, configure, and develop database applications using MySQL Connector/J 6.0, a JDBC driver for communicating with MySQL servers.

For notes detailing the changes in each release of Connector/J 6.0, see MySQL Connector/J 6.0 Release Notes.

For legal information, see the Legal Notices.

For help with using MySQL, please visit either the MySQL Forums or MySQL Mailing Lists, where you can discuss your issues with other MySQL users.

For additional documentation on MySQL products, including translations of the documentation into other languages, and downloadable versions in variety of formats, including HTML and PDF formats, see the MySQL Documentation Library.

Licensing information.  This product may include third-party software, used under license. If you are using a Commercial release of MySQL Connector/J 6.0, see this document for licensing information, including licensing information relating to third-party software that may be included in this Commercial release. If you are using a Community release of MySQL Connector/J 6.0, see this document for licensing information, including licensing information relating to third-party software that may be included in this Community release.

Document generated on: 2016-08-17 (revision: 48577)

Preface and Legal Notices

This manual describes how to install, configure, and develop database applications using MySQL Connector/J, the JDBC driver for communicating with MySQL servers.

Legal Notices

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Chapter 1 Overview of MySQL Connector/J

MySQL provides connectivity for client applications developed in the Java programming language with MySQL Connector/J. Connector/J implements the Java Database Connectivity (JDBC) API, as well as a number of value-adding extensions of it. It also supports the new X DevAPI.

MySQL Connector/J is a JDBC Type 4 driver. Different versions are available that are compatible with the JDBC 3.0 and JDBC 4.2 specifications (see Chapter 2, Connector/J Versions, and the MySQL and Java Versions They Support). The Type 4 designation means that the driver is a pure Java implementation of the MySQL protocol and does not rely on the MySQL client libraries.

For large-scale programs that use common design patterns of data access, consider using one of the popular persistence frameworks such as Hibernate, Spring's JDBC templates or Ibatis SQL Maps to reduce the amount of JDBC code for you to debug, tune, secure, and maintain.

Key Topics

For installation instructions for Connector/J, see Chapter 4, Connector/J Installation.

For help with connection strings, connection options, and setting up your connection through JDBC, see Section 6.1, “Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J”.

For information on connection pooling, see Chapter 8, Connection Pooling with Connector/J.

For information on multi-host connections, see Chapter 9, Multi-Host Connections.

Chapter 2 Connector/J Versions, and the MySQL and Java Versions They Support

There are currently two MySQL Connector/J versions available:

Connector/J 6.0 is a Type 4 pure Java JDBC 4.2 driver for the Java 8 platform. It provides compatibility with all the functionality of MySQL 5.5, 5.6, and 5.7. Connector/J 6.0 provides ease of development features, including auto-registration with the Driver Manager, standardized validity checks, categorized SQLExceptions, support for large update counts, support for local and offset date-time variants from the java.time package, support for JDBC-4.x XML processing, support for per connection client information, and support for the NCHAR, NVARCHAR and NCLOB data types.

Connector/J 5.1 is also a Type 4 pure Java JDBC driver that conforms to the JDBC 3.0, 4.0, ,4.1, and 4.2 specifications. It provides compatibility with all the functionality of MySQL 5.1, 5.5, 5.6, and 5.7. Connector/J 5.1 is covered by its own manual.

The following table summarizes the Connector/J versions available, along with the details of JDBC driver type, versions of the JDBC API supported, versions of MySQL Server supported, JRE supported, JDK required for building, and the support status for each of the Connector/J versions:

Table 2.1 Summary of Connector/J Versions

Connector/J version | JDBC version | MySQL Server version | JRE Supported | JDK Required for Compilation | Status
6.0 | 4.2 | 5.5, 5.6, 5.7 | 1.8.x | 1.8.x | Developer Milestone
5.1 | 3.0, 4.0, 4.1, 4.2 | 4.1, 5.0, 5.1, 5.5, 5.6*, 5.7* | 1.5.x, 1.6.x, 1.7.x, 1.8.x* | 1.5.x and 1.8.x | Recommended version

* JRE 1.8.x is required for Connector/J 5.1 to connect to MySQL 5.6 and 5.7 with SSL/TLS when using some cipher suites.

Chapter 3 What's New in Connector/J 6.0?

Here is a summary of major new features of Connector/J 6.0 (for details on the differences between the Connector/J 5.1 and 6.0 and for instructions on migrating, see Section 4.3.1, “Upgrading to MySQL Connector/J 6.0”):

It supports MySQL 5.5, 5.6, and 5.7. See Known Issues and Limitations for issues about support for MySQL 5.5 and 5.6.

It supports the JDBC 4.2 specification.

It is a MySQL driver for the Java 8 platform. For Java 7 or earlier, use Connector/J 5.1 instead.

It supports the new X DevAPI, through which native support by MySQL 5.7 for JSON, NoSQL, document collection, and other features are provided to Java applications. See Using MySQL as a Document Store, the X DevAPI User Guide, and MySQL Connector/J X DevAPI Reference for details .

Chapter 4 Connector/J Installation

Table of Contents

4.1 Installing Connector/J from a Binary Distribution

4.2 Installing the Driver and Configuring the CLASSPATH

4.3 Upgrading from an Older Version

4.3.1 Upgrading to MySQL Connector/J 6.0

4.4 Installing from the Development Source Tree

4.5 Testing Connector/J

MySQL Connector/J is distributed as a .zip or .tar.gz archive, available for download from the Connector/J Download page. The archive contains the sources and the JAR archive named mysql-connector-java-version-bin.jar.

You can install the Connector/J package using either the binary or source distribution. The binary distribution provides the easiest method for installation; the source distribution lets you customize your installation further. With either solution, you manually add the Connector/J location to your Java CLASSPATH.

If you are upgrading from a previous version, read the upgrade information in Section 4.3, “Upgrading from an Older Version” before continuing.

Connector/J is also available as part of the Maven project. For more information and to download the Connector/J JAR files, see the Maven repository.

4.1 Installing Connector/J from a Binary Distribution

For the easiest method of installation, use the binary distribution of the Connector/J package. Extract the JAR archive from the tar/gzip or zip archive to a suitable location, then optionally make the information about the JAR archive available by changing your CLASSPATH (see Section 4.2, “Installing the Driver and Configuring the CLASSPATH”).

Use the appropriate graphical or command-line utility to extract the distribution (for example, WinZip for the .zip archive, and tar for the .tar.gz archive). Because there are potentially long file names in the distribution, we use the GNU tar archive format. Use GNU tar (or an application that understands the GNU tar archive format) to unpack the .tar.gz variant of the distribution.

4.2 Installing the Driver and Configuring the CLASSPATH

Once you have extracted the distribution archive, you can install the driver by placing mysql-connector-java-version-bin.jar in your classpath, either by adding the full path to it to your CLASSPATH environment variable, or by directly specifying it with the command line switch -cp when starting the JVM.

To use the driver with the JDBC DriverManager, use com.mysql.cj.jdbc.Driver as the class that implements java.sql.Driver.

You can set the CLASSPATH environment variable under Unix, Linux, or OS X either locally for a user within the user's .profile, .login or other login file, or you can also set it globally by editing the global /etc/profile file.

For example, add the Connector/J driver to your CLASSPATH using one of the following forms, depending on your command shell:

# Bourne-compatible shell (sh, ksh, bash, zsh):
shell> export CLASSPATH=/path/mysql-connector-java-ver-bin.jar:$CLASSPATH

# C shell (csh, tcsh):
shell> setenv CLASSPATH /path/mysql-connector-java-ver-bin.jar:$CLASSPATH

For Windows platforms, you set the environment variable through the System Control Panel.

To use MySQL Connector/J with an application server such as GlassFish, Tomcat, or JBoss, read your vendor's documentation for more information on how to configure third-party class libraries, as most application servers ignore the CLASSPATH environment variable. For configuration examples for some J2EE application servers, see Chapter 8, Connection Pooling with Connector/J, Section 9.2, “Configuring Load Balancing with Connector/J”, and Section 9.4, “Advanced Load-balancing and Failover Configuration”. However, the authoritative source for JDBC connection pool configuration information for your particular application server is the documentation for that application server.

If you are developing servlets or JSPs, and your application server is J2EE-compliant, you can put the driver's .jar file in the WEB-INF/lib subdirectory of your webapp, as this is a standard location for third party class libraries in J2EE web applications.

You can also use the MysqlDataSource or MysqlConnectionPoolDataSource classes in the com.mysql.cj.jdbc.jdbc2.optional package, if your J2EE application server supports or requires them. The javax.sql.XADataSource interface is implemented using the com.mysql.cj.jdbc.jdbc2.optional.MysqlXADataSource class, which supports XA distributed transactions.

The various MysqlDataSource classes support the following parameters (through standard set mutators):

user

password

serverName (see the previous section about failover hosts)

databaseName

port

4.3 Upgrading from an Older Version

This section has information for users who are upgrading from one version of Connector/J to another, or to a new version of the MySQL server that supports a more recent level of JDBC. A newer version of Connector/J might include changes to support new features, improve existing functionality, or comply with new standards.

4.3.1 Upgrading to MySQL Connector/J 6.0

Upgrading an application developed for Connector/J 5.1 to use Connector/J 6.0 might require certain changes to your code or the environment in which it runs. Here are some changes for Connector/J going from 5.1 to 6.0, for which adjustments might be required:

4.3.1.1 Running on the Java 8 Platform

Connector/J 6.0 is created specifically to run on the Java 8 platform. While Java 8 is known to be strongly compatible with earlier Java versions, incompatibilities do exist, and code designed to work on Java 7 might need to be adjusted before being run on Java 8. Developers should refer to the incompatibility information provided by Oracle.

4.3.1.2 Changes in Connection Properties

A complete list of Connector/J 6.0 connection properties are available in Setting Configuration Properties. The following are connection properties that have been changed going from Connector/5.1 to 6.0. Make sure you do not use any of the removed properties during connection.

Properties that have been removed:

useDynamicCharsetInfo

useBlobToStoreUTF8OutsideBMP , utf8OutsideBmpExcludedColumnNamePattern, and utf8OutsideBmpIncludedColumnNamePattern: MySQL 5.5 and later supports the utf8mb4 character set, which is the character set that should be used by Connector/J applications for supporting characters beyond the Basic Multilingual Plane (BMP) of Unicode Version 3.

useJvmCharsetConverters: JVM character set conversion is now used in all cases

The following date and time properties:

dynamicCalendars

noTzConversionForTimeType

noTzConversionForDateType

cacheDefaultTimezone

useFastIntParsing

useFastDateParsing

useJDBCCompliantTimezoneShift

useLegacyDatetimeCode

useSSPSCompatibleTimezoneShift

useTimezone

useGmtMillisForDatetimes

dumpMetadataOnColumnNotFound

relaxAutoCommit

strictFloatingPoint

runningCTS13

retainStatementAfterResultSetClose

Properties that have been added:

mysqlx.useAsyncProtocol

Property that has its name changed:

com.mysql.jdbc.faultInjection.serverCharsetIndex changed to com.mysql.cj.testsuite.faultInjection.serverCharsetIndex

loadBalanceEnableJMX to ha.enableJMX

replicationEnableJMX to ha.enableJMX

4.3.1.3 Changes in the Connector/J API

This section describes the changes to the Connector/J API going from version 5.1 to 6.0. You might need to adjust your API calls accordingly:

The name of the class that implements java.sql.Driver in MySQL Connector/J has changed from com.mysql.jdbc.Driver to com.mysql.cj.jdbc.Driver. The old class name has been deprecated.

The names of these commonly-used interfaces have also been changed:

ExceptionInterceptor: from com.mysql.jdbc.ExceptionInterceptor to com.mysql.cj.api.exceptions.ExceptionInterceptor

StatementInterceptor: from com.mysql.jdbc.StatementInterceptorV2 to com.mysql.cj.api.jdbc.interceptors.StatementInterceptorV2

ConnectionLifecycleInterceptor: from com.mysql.jdbc.ConnectionLifecycleInterceptor to com.mysql.cj.api.jdbc.interceptors.ConnectionLifecycleInterceptor

AuthenticationPlugin: from com.mysql.jdbc.AuthenticationPlugin to com.mysql.cj.api.authentication.AuthenticationPlugin

BalanceStrategy: from com.mysql.jdbc.BalanceStrategy to com.mysql.cj.api.jdbc.ha.BalanceStrategy.

4.3.1.4 Changes for Build Properties

A number of Ant properties for building Connector/J from source have been renamed; see Table 4.1, “Changes with the Build Properties from Connector/J 5.1 to 6.0”

Table 4.1 Changes with the Build Properties from Connector/J 5.1 to 6.0

Old name | New name
com.mysql.jdbc.extra.libs | com.mysql.cj.extra.libs
com.mysql.jdbc.jdk | com.mysql.cj.build.jdk
debug.enable | com.mysql.cj.build.addDebugInfo
com.mysql.jdbc.noCleanBetweenCompiles | com.mysql.cj.build.noCleanBetweenCompiles
com.mysql.jdbc.commercialBuild | com.mysql.cj.build.commercial
com.mysql.jdbc.filterLicense | com.mysql.cj.build.filterLicense
com.mysql.jdbc.noCryptoBuild | com.mysql.cj.build.noCrypto
com.mysql.jdbc.noSources | com.mysql.cj.build.noSources
com.mysql.jdbc.noMavenSources | com.mysql.cj.build.noMavenSources
major_version | com.mysql.cj.build.driver.version.major
minor_version | com.mysql.cj.build.driver.version.minor
subminor_version | com.mysql.cj.build.driver.version.subminor
version_status | com.mysql.cj.build.driver.version.status
extra.version | com.mysql.cj.build.driver.version.extra
snapshot.version | com.mysql.cj.build.driver.version.snapshot
version | com.mysql.cj.build.driver.version
full.version | com.mysql.cj.build.driver.version.full
prodDisplayName | com.mysql.cj.build.driver.displayName
prodName | com.mysql.cj.build.driver.name
fullProdName | com.mysql.cj.build.driver.fullName
buildDir | com.mysql.cj.build.dir
buildDriverDir | com.mysql.cj.build.dir.driver
mavenUploadDir | com.mysql.cj.build.dir.maven
distDir | com.mysql.cj.dist.dir
toPackage | com.mysql.cj.dist.dir.prepare
packageDest | com.mysql.cj.dist.dir.package
com.mysql.jdbc.docs.sourceDir | com.mysql.cj.dist.dir.prebuilt.docs

4.3.1.5 Change for Test Properties

A number of Ant properties for testing Connecotr/J have been renamed or removed; see Table 4.2, “Changes with the Test Properties from Connector/J 5.1 to 6.0”

Table 4.2 Changes with the Test Properties from Connector/J 5.1 to 6.0

Old name | New name
buildTestDir | com.mysql.cj.testsuite.build.dir
junit.results | com.mysql.cj.testsuite.junit.results
com.mysql.jdbc.testsuite.jvm | com.mysql.cj.testsuite.jvm
test | com.mysql.cj.testsuite.test.class
methods | com.mysql.cj.testsuite.test.methods
com.mysql.jdbc.testsuite.url | com.mysql.cj.testsuite.url
com.mysql.jdbc.testsuite.admin-url | com.mysql.cj.testsuite.url.admin
com.mysql.jdbc.testsuite.ClusterUrl | com.mysql.cj.testsuite.url.cluster
com.mysql.jdbc.testsuite.url.sha256default | com.mysql.cj.testsuite.url.openssl
com.mysqlx.testsuite.url | com.mysql.cj.testsuite.mysqlx.url
com.mysql.fabric.testsuite.hostname | com.mysql.cj.testsuite.fabric.hostname
com.mysql.fabric.testsuite.port | com.mysql.cj.testsuite.fabric.port
com.mysql.fabric.testsuite.database | com.mysql.cj.testsuite.fabric.database
com.mysql.fabric.testsuite.username | com.mysql.cj.testsuite.fabric.username
com.mysql.fabric.testsuite.password | com.mysql.cj.testsuite.fabric.password
com.mysql.fabric.testsuite.fabricUsername | com.mysql.cj.testsuite.fabric.fabricUsername
com.mysql.fabric.testsuite.fabricPassword | com.mysql.cj.testsuite.fabric.fabricPassword
com.mysql.fabric.testsuite.global.host | com.mysql.cj.testsuite.fabric.global.host
com.mysql.fabric.testsuite.global.port | com.mysql.cj.testsuite.fabric.global.port
com.mysql.fabric.testsuite.shard1.host | com.mysql.cj.testsuite.fabric.shard1.host
com.mysql.fabric.testsuite.shard1.port | com.mysql.cj.testsuite.fabric.shard1.port
com.mysql.fabric.testsuite.shard2.host | com.mysql.cj.testsuite.fabric.shard2.host
com.mysql.fabric.testsuite.shard2.port | com.mysql.cj.testsuite.fabric.shard2.port
com.mysql.jdbc.testsuite.cantGrant | com.mysql.cj.testsuite.cantGrant
com.mysql.jdbc.testsuite.no-multi-hosts-tests | com.mysql.cj.testsuite.disable.multihost.tests
com.mysql.jdbc.test.ds.host | com.mysql.cj.testsuite.ds.host
com.mysql.jdbc.test.ds.port | com.mysql.cj.testsuite.ds.port
com.mysql.jdbc.test.ds.db | com.mysql.cj.testsuite.ds.db
com.mysql.jdbc.test.ds.user | com.mysql.cj.testsuite.ds.user
com.mysql.jdbc.test.ds.password | com.mysql.cj.testsuite.ds.password
com.mysql.jdbc.test.tabletype | com.mysql.cj.testsuite.loadstoreperf.tabletype
com.mysql.jdbc.testsuite.loadstoreperf.useBigResults | com.mysql.cj.testsuite.loadstoreperf.useBigResults
com.mysql.jdbc.testsuite.MiniAdminTest.runShutdown | com.mysql.cj.testsuite.miniAdminTest.runShutdown
com.mysql.jdbc.testsuite.noDebugOutput | com.mysql.cj.testsuite.noDebugOutput
com.mysql.jdbc.testsuite.retainArtifacts | com.mysql.cj.testsuite.retainArtifacts
com.mysql.jdbc.testsuite.runLongTests | com.mysql.cj.testsuite.runLongTests
com.mysql.jdbc.test.ServerController.basedir | com.mysql.cj.testsuite.serverController.basedir
com.mysql.jdbc.ReplicationConnection.isSlave | com.mysql.cj.testsuite.replicationConnection.isSlave
com.mysql.jdbc.test.isLocalHostnameReplacement | Removed
com.mysql.jdbc.testsuite.driver | Removed
com.mysql.jdbc.testsuite.url.default | Removed. No longer needed, as multi-JVM tests have been removed from the test suite.

4.3.1.6 Other Changes

Here are other changes with Connector/J 6.0:

Removed FabricMySQLDriver. Instead of using a separate driver, you can now obtain a connection that uses Fabric just by using the jdbc:mysql:fabric:// scheme.

Removed ReplicationDriver. Instead of using a separate driver, you can now obtain a connection for a replication setup just by using the jdbc:mysql:replication:// scheme.

Requires the following third-party libraries to work:

Protocol Buffers

Javassist (only required for building Connector/J 6.0 from source)

4.4 Installing from the Development Source Tree

Caution

Read this section only if you are interested in helping us test our new code. To just get MySQL Connector/J up and running on your system, use a standard binary release distribution.

To install MySQL Connector/J from the development source tree, make sure that you have the following software on your system:

A Git client, to check out the sources from our GitHub repository (available from http://git-scm.com/downloads).

Apache Ant version 1.8.2 or newer (available from http://ant.apache.org/).

JDK 1.8.x.

JUnit 4.1.2 (available from https://github.com/junit-team/junit/wiki/Download-and-Install).

Javaassist 3.19 or newer (available from http://jboss-javassist.github.io/javassist/).

Protocol Buffers Java API 2.6.0 or newer (available from, for example, the Maven Central Repository).

The required .jar files from the Hibernate ORM 4.1 or 4.2 Final release bundle (available at http://sourceforge.net/projects/hibernate/files/hibernate4/).

To check out and compile MySQL Connector/J, follow these steps:

Check out the code from the source code repository for MySQL Connector/J located on GitHub at https://github.com/mysql/mysql-connector-j. The latest release of the Connector/J 6.0 series is on the release/6.0 branch; use the following command to check it out:

shell> git clone --branch release/6.0 https://github.com/mysql/mysql-connector-j.git

Under the current directory, the commands create a mysql-connector-j subdirectory , which contains the code you want.

Make sure that you have JDK 1.8.x installed.

Place the required junit.jar, javaassist.jar, and protobuf-java-x.y.z.jar files in a separate directory—for example, /home/username/ant-extralibs.

In the same directory for extra libraries described in the last step, create a directory named hibernate4, and put under it all the .jar files you can find under the /lib/required/ folder in the Hibernate ORM 4 Final release bundle.

Change your current working directory to the mysql-connector-j directory created in step 1 above.

In the directory, create a file named build.properties to indicate to Ant the locations of the root directories for your JDK 1.8.x installation, as well as the location of the extra libraries. The file should contain the following property settings, with the “path_to_*” parts replaced by the appropriate filepaths:

com.mysql.cj.build.jdk=path_to_jdk_1.8
com.mysql.cj.extra.libs=path_to_folder_for_extra_libraries

Alternatively, you can set the values of those properties through the Ant -D options.

Issue the following command to compile the driver and create a .jar file for Connector/J:

shell> ant dist

This creates a build directory in the current directory, where all the build output goes. A directory is created under the build directory, whose name includes the version number of the release you are building. That directory contains the sources, the compiled .class files, and a .jar file for deployment. For more information and other possible targets, including those that create a fully packaged distribution, issue the following command:

shell> ant -projecthelp

Install the newly created .jar file for the JDBC driver as you would install a binary .jar file you download from MySQL by following the instructions given in Section 4.2, “Installing the Driver and Configuring the CLASSPATH”.

Note that a package containing both the binary and source code for Connector/J 6.0 can also be downloaded from the Connector/J Download page.

Note

Going from Connector/J 5.1 to 6.0, a number of Ant properties for building Connecotr/J have been renamed or removed; see Section 4.3.1.4, “Changes for Build Properties” for details.

4.5 Testing Connector/J

The Connector/J source code repository or packages that are shipped with source code include an extensive test suite, containing test cases that can be executed independently. The test cases are divided into the following categories:

Unit tests: They are methods located in packages aligning with the classes that they test.

Functional tests: Classes from the package testsuite.simple. Include test code for the main features of the Connector/J.

Performance tests: Classes from the package testsuite.perf. Include test code to make measurements for the performance of Connector/J.

Fabric tests: Classes from the package testsuite.fabric. Includes the code to test Fabric-specific features. These tests require the setting of some special properties that are not documented here. Consult the code or the Fabric-related targets in the bundled Ant build file, build.xml.

Regression tests: Classes from the package testsuite.regression. Includes code for testing bug and regression fixes.

MySQL X tests: Classes from the package testsuite.mysqlx and testsuite.x for testing MySQL X functionality.

The bundled Ant build file contains the targets test, test-fabric-setupand test-fabric, which can facilitate the process of running the Connector/J tests; see the target descriptions in the build file for details. Besides the requirements for building Connector/J from the source code described in Section 4.4, “Installing from the Development Source Tree”, a number of the tests also require the File System Service Provider 1.2 for the Java Naming and Directory Interface (JNDI), available at http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-java-plat-419418.html)—place the jar files downloaded from there into the lib directory or in the directory pointed to by the property com.mysql.cj.extra.libs.

To run the test using Ant, in addition to the properties required for Section 4.4, “Installing from the Development Source Tree”, you must set the following properties in the build.properties file or through the Ant -D options:

com.mysql.cj.testsuite.url: it specifies the JDBC URL for connection to a MySQL test server; see Section 6.1, “Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J”.

com.mysql.cj.testsuite.jvm: the JVM to be used for the tests. If the property is not set, the JVM supplied with com.mysql.cj.build.jdk will be used.

After setting these parameters, run the tests with Ant in the following ways:

Building the test target with ant test runs all test cases by default on a single server instance. If you want to run a particular test case, put the test's fully qualified class names in the test variable; for example:

shell > ant -Dtest=testsuite.simple.StringUtilsTest test

You can also run individual tests in a test case by specifying the names of the corresponding methods in the methods variable, separating multiple methods by commas; for example:

shell > ant -Dtest=testsuite.simple.StringUtilsTest -Dmethods=testIndexOfIgnoreCase,testGetBytes test

While the test results are partially reported by the console, complete reports in HTML and XML formats are provided. View the HTML report by opening build/junit/unitregress/report/index.html. XML version of the reports are located in the folder build/junit/unitregress.

Note

Going from Connector/J 5.1 to 6.0, a number of Ant properties for testing Connecotr/J have been renamed or removed; see Section 4.3.1.5, “Change for Test Properties” for details.

Chapter 5 Connector/J Examples

Examples of using Connector/J are located throughout this document. This section provides a summary and links to these examples.

Example 7.1, “Connector/J: Obtaining a connection from the DriverManager”

Example 7.2, “Connector/J: Using java.sql.Statement to execute a SELECT query”

Example 7.3, “Connector/J: Calling Stored Procedures”

Example 7.4, “Connector/J: Using Connection.prepareCall()”

Example 7.5, “Connector/J: Registering output parameters”

Example 7.6, “Connector/J: Setting CallableStatement input parameters”

Example 7.7, “Connector/J: Retrieving results and output parameter values”

Example 7.8, “Connector/J: Retrieving AUTO_INCREMENT column values using Statement.getGeneratedKeys()”

Example 7.9, “Connector/J: Retrieving AUTO_INCREMENT column values using SELECT LAST_INSERT_ID()”

Example 7.10, “Connector/J: Retrieving AUTO_INCREMENT column values in Updatable ResultSets”

Example 8.1, “Connector/J: Using a connection pool with a J2EE application server”

Example 15.1, “Connector/J: Example of transaction with retry logic”

Chapter 6 Connector/J (JDBC) Reference

Table of Contents

6.1 Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

6.1.1 Properties Files for the useConfigs Option

6.2 JDBC API Implementation Notes

6.3 Java, JDBC and MySQL Types

6.4 Using Character Sets and Unicode

6.5 Connecting Securely Using SSL

6.6 Connecting Using PAM Authentication

6.7 Using Master/Slave Replication with ReplicationConnection

6.8 Mapping MySQL Error Numbers to JDBC SQLState Codes

This section of the manual contains reference material for MySQL Connector/J.

6.1 Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

The name of the class that implements java.sql.Driver in MySQL Connector/J is com.mysql.cj.jdbc.Driver.

JDBC URL Format

The general format for a JDBC URL for connecting to a MySQL server is as follows, with items in square brackets ([ ]) being optional:

jdbc:mysql://[host1][:port1][,[host2][:port2]]...[/[database]] »
[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

Here is a simple example for a connection URL:

jdbc:mysql://localhost:3306/sakila?profileSQL=true

Supply multiple hosts for a server failover setup (see Chapter 9, Multi-Host Connections for details):

# Connection URL for a server failover setup:
jdbc:mysql//primaryhost,secondaryhost1,secondaryhost2/test

There are specialized URL schemes for configuring Connector/J's multi-host functions like load balancing and replication; here are some examples (see Chapter 9, Multi-Host Connections for details):

# Connection URL for load balancing:
jdbc:mysql:loadbalance://localhost:3306,localhost:3310/sakila

# Connection URL for server replication:
jdbc:mysql:replication://master,slave1,slave2,slave3/test

Host and Port

If no hosts are not specified, the host name defaults to 127.0.0.1. If the port for a host is not specified, it defaults to 3306, the default port number for MySQL servers.

Initial Database for Connection

If the database is not specified, the connection is made with no default database. In this case, either call the setCatalog() method on the Connection instance, or fully specify table names using the database name (that is, SELECT dbname.tablename.colname FROM dbname.tablename...) in your SQL. Opening a connection without specifying the database to use is generally only useful when building tools that work with multiple databases, such as GUI database managers.

Note

Always use the Connection.setCatalog() method to specify the desired database in JDBC applications, rather than the USE database statement.

Alternate Format for JDBC URLs

The following is an alternate format for JDBC URLs connecting to a MySQL server, which is mandatory for IPv6 connections, but can also be used with IPv4 (items in square brackets ([ ]) are optional):

jdbc:mysql://address=(key1=value)[(key2=value)]...[,address=(key3=value)[(key4=value)]...]...[/[database]]»
[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

Supported key-value pairs include:

(protocol=tcp), or (protocol=pipe) for named pipes on Windows.

(path=path_to_pipe) for path of named pipes. Default value for the path is \\.\pipe\MySQL. Use the key-value pair to specify a custom named pipe.

(host=hostname) for TCP connections.

(port=port_number) for TCP connections.

For example:

jdbc:mysql://address=(protocol=tcp)(host=localhost)(port=3306)/db

Notice that the alternate format greatly simplifies the URL for a named pipe connection on Windows. For example, to use the default named pipe of “\\.\pipe\MySQL,” just specifies:

jdbc:mysql://address=(protocol=pipe)/test

To use the custom named pipe of “\\.\pipe\MySQL57” :

jdbc:mysql://address=(protocol=pipe)(path=\\.\pipe\MySQL57)/test

Keys other than protocol, path, host, and port are treated as host-specific configuration properties, which allow per-host overrides of configuration properties set for multi-host connections (that is, when using failover, load balancing, or replication). For example:

# Connection URL in the alternate format for a server failover setup:
jdbc:mysql://address=(protocol=tcp)(host=primaryhost)(port=3306),»
address=(protocol=tcp)(host=secondaryhost1)(port=3310)(user=test2)/test

# Connection URL in the alternate format for a load balancing setup:
jdbc:mysql:loadbalance://address=(protocol=tcp)(host=localhost)(port=3306)(user=test1),»
address=(protocol=tcp)(host=localhost)(port=3310)(user=test2)/sakila

# Connection URL in the alternate format for a server replication setup:
jdbc:mysql:replication://address=(protocol=tcp)(host=master)(port=3306)(user=test1),»
address=(protocol=tcp)(host=slave1)(port=3310)(user=test2)/test

Limit the overrides to user, password, network timeouts, and statement and metadata cache sizes; the effects of other per-host overrides are not defined.

The ways to set other configuration properties for the connection are the same for the general and the alternate URL formats; see Setting Configuration Properties.

Setting Configuration Properties

Configuration properties define how Connector/J will make a connection to a MySQL server. Unless otherwise noted, properties can be set for a DataSource object or for a Connection object.

Configuration properties can be set in one of the following ways:

Using the set*() methods on MySQL implementations of java.sql.DataSource (which is the preferred method when using implementations of java.sql.DataSource):

com.mysql.cj.jdbc.jdbc2.optional.MysqlDataSource

com.mysql.cj.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource

As a key/value pair in the java.util.Properties instance passed to DriverManager.getConnection() or Driver.connect()

As a JDBC URL parameter in the URL given to java.sql.DriverManager.getConnection(), java.sql.Driver.connect() or the MySQL implementations of the javax.sql.DataSource setURL() method. If you specify a configuration property in the URL without providing a value for it, nothing will be set; for example, adding useServerPrepStmts alone to the URL does not make Connector/J use server-side prepared statements; you need to add useServerPrepStmts=true.

Note

If the mechanism you use to configure a JDBC URL is XML-based, use the XML character literal &amp; to separate configuration parameters, as the ampersand is a reserved character for XML.

The properties are listed in the following tables.

Authentication. 

Properties and Descriptions

user

The user to connect as

Since version: all versions

password

The password to use when connecting

Since version: all versions

Connection. 

Properties and Descriptions

connectionAttributes

A comma-delimited list of user-defined key:value pairs (in addition to standard MySQL-defined key:value pairs) to be passed to MySQL Server for display as connection attributes in the PERFORMANCE_SCHEMA.SESSION_CONNECT_ATTRS table. Example usage: connectionAttributes=key1:value1,key2:value2 This functionality is available for use with MySQL Server version 5.6 or later only. Earlier versions of MySQL Server do not support connection attributes, causing this configuration option to be ignored. Setting connectionAttributes=none will cause connection attribute processing to be bypassed, for situations where Connection creation/initialization speed is critical.

Since version: 5.1.25

connectionLifecycleInterceptors

A comma-delimited list of classes that implement "com.mysql.cj.api.jdbc.interceptors.ConnectionLifecycleInterceptor" that should notified of connection lifecycle events (creation, destruction, commit, rollback, setCatalog and setAutoCommit) and potentially alter the execution of these commands. ConnectionLifecycleInterceptors are "stackable", more than one interceptor may be specified via the configuration property as a comma-delimited list, with the interceptors executed in order from left to right.

Since version: 5.1.4

useConfigs

Load the comma-delimited list of configuration properties before parsing the URL or applying user-specified properties. These configurations are explained in the 'Configurations' of the documentation.

Since version: 3.1.5

authenticationPlugins

Comma-delimited list of classes that implement com.mysql.cj.api.mysqla.authentication.AuthenticationPlugin and which will be used for authentication unless disabled by "disabledAuthenticationPlugins" property.

Since version: 5.1.19

createDatabaseIfNotExist

Creates the database given in the URL if it doesn't yet exist. Assumes the configured user has permissions to create databases.

Default: false

Since version: 3.1.9

defaultAuthenticationPlugin

Name of a class implementing com.mysql.cj.api.mysqla.authentication.AuthenticationPlugin which will be used as the default authentication plugin (see below). It is an error to use a class which is not listed in "authenticationPlugins" nor it is one of the built-in plugins. It is an error to set as default a plugin which was disabled with "disabledAuthenticationPlugins" property. It is an error to set this value to null or the empty string (i.e. there must be at least a valid default authentication plugin specified for the connection, meeting all constraints listed above).

Default: com.mysql.cj.mysqla.authentication.MysqlNativePasswordPlugin

Since version: 5.1.19

detectCustomCollations

Should the driver detect custom charsets/collations installed on server (true/false, defaults to 'false'). If this option set to 'true' driver gets actual charsets/collations from server each time connection establishes. This could slow down connection initialization significantly.

Default: false

Since version: 5.1.29

disabledAuthenticationPlugins

Comma-delimited list of classes implementing com.mysql.cj.api.mysqla.authentication.AuthenticationPlugin or mechanisms, i.e. "mysql_native_password". The authentication plugins or mechanisms listed will not be used for authentication which will fail if it requires one of them. It is an error to disable the default authentication plugin (either the one named by "defaultAuthenticationPlugin" property or the hard-coded one if "defaultAuthenticationPlugin" property is not set).

Since version: 5.1.19

disconnectOnExpiredPasswords

If "disconnectOnExpiredPasswords" is set to "false" and password is expired then server enters "sandbox" mode and sends ERR(08001, ER_MUST_CHANGE_PASSWORD) for all commands that are not needed to set a new password until a new password is set.

Default: true

Since version: 5.1.23

interactiveClient

Set the CLIENT_INTERACTIVE flag, which tells MySQL to timeout connections based on INTERACTIVE_TIMEOUT instead of WAIT_TIMEOUT

Default: false

Since version: 3.1.0

passwordCharacterEncoding

What character encoding is used for passwords? Leaving this set to the default value (null), uses the value set in "characterEncoding" if there is one, otherwise uses UTF-8 as default encoding. If the password contains non-ASCII characters, the password encoding must match what server encoding was set to when the password was created. For passwords in other character encodings, the encoding will have to be specified with this property (or with "characterEncoding"), as it's not possible for the driver to auto-detect this.

Since version: 5.1.7

propertiesTransform

An implementation of com.mysql.cj.api.conf.ConnectionPropertiesTransform that the driver will use to modify URL properties passed to the driver before attempting a connection

Since version: 3.1.4

rollbackOnPooledClose

Should the driver issue a rollback() when the logical connection in a pool is closed?

Default: true

Since version: 3.0.15

useAffectedRows

Don't set the CLIENT_FOUND_ROWS flag when connecting to the server (not JDBC-compliant, will break most applications that rely on "found" rows vs. "affected rows" for DML statements), but does cause "correct" update counts from "INSERT ... ON DUPLICATE KEY UPDATE" statements to be returned by the server.

Default: false

Since version: 5.1.7

Session. 

Properties and Descriptions

characterEncoding

What character encoding should the driver use when dealing with strings? (defaults is to 'autodetect')

Since version: 1.1g

characterSetResults

Character set to tell the server to return results as.

Since version: 3.0.13

connectionCollation

If set, tells the server to use this collation via 'set collation_connection'

Since version: 3.0.13

sessionVariables

A comma-separated list of name/value pairs to be sent as SET SESSION ... to the server when the driver connects.

Since version: 3.1.8

useOldUTF8Behavior

Use the UTF-8 behavior the driver did when communicating with 4.0 and older servers

Default: false

Since version: 3.1.6

Networking. 

Properties and Descriptions

socksProxyHost

Name or IP address of SOCKS host to connect through.

Since version: 5.1.34

socksProxyPort

Port of SOCKS server.

Default: 1080

Since version: 5.1.34

socketFactory

The name of the class that the driver should use for creating socket connections to the server. This class must implement the interface 'com.mysql.cj.api.io.SocketFactory' and have public no-args constructor.

Default: com.mysql.cj.core.io.StandardSocketFactory

Since version: 3.0.3

connectTimeout

Timeout for socket connect (in milliseconds), with 0 being no timeout. Only works on JDK-1.4 or newer. Defaults to '0'.

Default: 0

Since version: 3.0.1

socketTimeout

Timeout on network socket operations (0, the default means no timeout).

Default: 0

Since version: 3.0.1

localSocketAddress

Hostname or IP address given to explicitly configure the interface that the driver will bind the client side of the TCP/IP connection to when connecting.

Since version: 5.0.5

maxAllowedPacket

Maximum allowed packet size to send to server. If not set, the value of system variable 'max_allowed_packet' will be used to initialize this upon connecting. This value will not take effect if set larger than the value of 'max_allowed_packet'. Also, due to an internal dependency with the property "blobSendChunkSize", this setting has a minimum value of "8203" if "useServerPrepStmts" is set to "true".

Default: 65535

Since version: 5.1.8

tcpKeepAlive

If connecting using TCP/IP, should the driver set SO_KEEPALIVE?

Default: true

Since version: 5.0.7

tcpNoDelay

If connecting using TCP/IP, should the driver set SO_TCP_NODELAY (disabling the Nagle Algorithm)?

Default: true

Since version: 5.0.7

tcpRcvBuf

If connecting using TCP/IP, should the driver set SO_RCV_BUF to the given value? The default value of '0', means use the platform default value for this property)

Default: 0

Since version: 5.0.7

tcpSndBuf

If connecting using TCP/IP, should the driver set SO_SND_BUF to the given value? The default value of '0', means use the platform default value for this property)

Default: 0

Since version: 5.0.7

tcpTrafficClass

If connecting using TCP/IP, should the driver set traffic class or type-of-service fields ?See the documentation for java.net.Socket.setTrafficClass() for more information.

Default: 0

Since version: 5.0.7

useCompression

Use zlib compression when communicating with the server (true/false)? Defaults to 'false'.

Default: false

Since version: 3.0.17

useUnbufferedInput

Don't use BufferedInputStream for reading data from the server

Default: true

Since version: 3.0.11

Security. 

Properties and Descriptions

allowMultiQueries

Allow the use of ';' to delimit multiple queries during one statement (true/false), defaults to 'false', and does not affect the addBatch() and executeBatch() methods, which instead rely on rewriteBatchStatements.

Default: false

Since version: 3.1.1

useSSL

Use SSL when communicating with the server (true/false), default is 'true' when connecting to MySQL 5.5.45+, 5.6.26+ or 5.7.6+, otherwise default is 'false'

Default: false

Since version: 3.0.2

requireSSL

Require server support of SSL connection if useSSL=true? (defaults to 'false').

Default: false

Since version: 3.1.0

verifyServerCertificate

If "useSSL" is set to "true", should the driver verify the server's certificate? When using this feature, the keystore parameters should be specified by the "clientCertificateKeyStore*" properties, rather than system properties. Default is 'false' when connecting to MySQL 5.5.45+, 5.6.26+ or 5.7.6+ and "useSSL" was not explicitly set to "true". Otherwise default is 'true'

Default: true

Since version: 5.1.6

clientCertificateKeyStoreUrl

URL to the client certificate KeyStore (if not specified, use defaults)

Since version: 5.1.0

clientCertificateKeyStoreType

KeyStore type for client certificates (NULL or empty means use the default, which is "JKS". Standard keystore types supported by the JVM are "JKS" and "PKCS12", your environment may have more available depending on what security products are installed and available to the JVM.

Default: JKS

Since version: 5.1.0

clientCertificateKeyStorePassword

Password for the client certificates KeyStore

Since version: 5.1.0

trustCertificateKeyStoreUrl

URL to the trusted root certificate KeyStore (if not specified, use defaults)

Since version: 5.1.0

trustCertificateKeyStoreType

KeyStore type for trusted root certificates (NULL or empty means use the default, which is "JKS". Standard keystore types supported by the JVM are "JKS" and "PKCS12", your environment may have more available depending on what security products are installed and available to the JVM.

Default: JKS

Since version: 5.1.0

trustCertificateKeyStorePassword

Password for the trusted root certificates KeyStore

Since version: 5.1.0

enabledSSLCipherSuites

If "useSSL" is set to "true", overrides the cipher suites enabled for use on the underlying SSL sockets. This may be required when using external JSSE providers or to specify cipher suites compatible with both MySQL server and used JVM.

Since version: 5.1.35

allowLoadLocalInfile

Should the driver allow use of 'LOAD DATA LOCAL INFILE...' (defaults to 'true').

Default: true

Since version: 3.0.3

allowUrlInLocalInfile

Should the driver allow URLs in 'LOAD DATA LOCAL INFILE' statements?

Default: false

Since version: 3.1.4

allowPublicKeyRetrieval

Allows special handshake roundtrip to get server RSA public key directly from server.

Default: false

Since version: 5.1.31

paranoid

Take measures to prevent exposure sensitive information in error messages and clear data structures holding sensitive data when possible? (defaults to 'false')

Default: false

Since version: 3.0.1

serverRSAPublicKeyFile

File path to the server RSA public key file for sha256_password authentication. If not specified, the public key will be retrieved from the server.

Since version: 5.1.31

Statements. 

Properties and Descriptions

continueBatchOnError

Should the driver continue processing batch commands if one statement fails. The JDBC spec allows either way (defaults to 'true').

Default: true

Since version: 3.0.3

dontTrackOpenResources

The JDBC specification requires the driver to automatically track and close resources, however if your application doesn't do a good job of explicitly calling close() on statements or result sets, this can cause memory leakage. Setting this property to true relaxes this constraint, and can be more memory efficient for some applications. Also the automatic closing of the Statement and current ResultSet in Statement.closeOnCompletion() and Statement.getMoreResults ([Statement.CLOSE_CURRENT_RESULT | Statement.CLOSE_ALL_RESULTS]), respectively, ceases to happen. This property automatically sets holdResultsOpenOverStatementClose=true.

Default: false

Since version: 3.1.7

queryTimeoutKillsConnection

If the timeout given in Statement.setQueryTimeout() expires, should the driver forcibly abort the Connection instead of attempting to abort the query?

Default: false

Since version: 5.1.9

statementInterceptors

A comma-delimited list of classes that implement "com.mysql.cj.api.jdbc.interceptors.StatementInterceptor" that should be placed "in between" query execution to influence the results. StatementInterceptors are "chainable", the results returned by the "current" interceptor will be passed on to the next in in the chain, from left-to-right order, as specified in this property.

Since version: 5.1.1

Prepared Statements. 

Properties and Descriptions

allowNanAndInf

Should the driver allow NaN or +/- INF values in PreparedStatement.setDouble()?

Default: false

Since version: 3.1.5

autoClosePStmtStreams

Should the driver automatically call .close() on streams/readers passed as arguments via set*() methods?

Default: false

Since version: 3.1.12

compensateOnDuplicateKeyUpdateCounts

Should the driver compensate for the update counts of "ON DUPLICATE KEY" INSERT statements (2 = 1, 0 = 1) when using prepared statements?

Default: false

Since version: 5.1.7

emulateUnsupportedPstmts

Should the driver detect prepared statements that are not supported by the server, and replace them with client-side emulated versions?

Default: true

Since version: 3.1.7

generateSimpleParameterMetadata

Should the driver generate simplified parameter metadata for PreparedStatements when no metadata is available either because the server couldn't support preparing the statement, or server-side prepared statements are disabled?

Default: false

Since version: 5.0.5

processEscapeCodesForPrepStmts

Should the driver process escape codes in queries that are prepared? Default escape processing behavior in non-prepared statements must be defined with the property 'enableEscapeProcessing'.

Default: true

Since version: 3.1.12

useServerPrepStmts

Use server-side prepared statements if the server supports them?

Default: false

Since version: 3.1.0

useStreamLengthsInPrepStmts

Honor stream length parameter in PreparedStatement/ResultSet.setXXXStream() method calls (true/false, defaults to 'true')?

Default: true

Since version: 3.0.2

Result Sets. 

Properties and Descriptions

clobberStreamingResults

This will cause a 'streaming' ResultSet to be automatically closed, and any outstanding data still streaming from the server to be discarded if another query is executed before all the data has been read from the server.

Default: false

Since version: 3.0.9

emptyStringsConvertToZero

Should the driver allow conversions from empty string fields to numeric values of '0'?

Default: true

Since version: 3.1.8

holdResultsOpenOverStatementClose

Should the driver close result sets on Statement.close() as required by the JDBC specification?

Default: false

Since version: 3.1.7

jdbcCompliantTruncation

Should the driver throw java.sql.DataTruncation exceptions when data is truncated as is required by the JDBC specification when connected to a server that supports warnings (MySQL 4.1.0 and newer)? This property has no effect if the server sql-mode includes STRICT_TRANS_TABLES.

Default: true

Since version: 3.1.2

maxRows

The maximum number of rows to return (0, the default means return all rows).

Default: -1

Since version: all versions

netTimeoutForStreamingResults

What value should the driver automatically set the server setting 'net_write_timeout' to when the streaming result sets feature is in use? (value has unit of seconds, the value '0' means the driver will not try and adjust this value)

Default: 600

Since version: 5.1.0

padCharsWithSpace

If a result set column has the CHAR type and the value does not fill the amount of characters specified in the DDL for the column, should the driver pad the remaining characters with space (for ANSI compliance)?

Default: false

Since version: 5.0.6

populateInsertRowWithDefaultValues

When using ResultSets that are CONCUR_UPDATABLE, should the driver pre-populate the "insert" row with default values from the DDL for the table used in the query so those values are immediately available for ResultSet accessors? This functionality requires a call to the database for metadata each time a result set of this type is created. If disabled (the default), the default values will be populated by the an internal call to refreshRow() which pulls back default values and/or values changed by triggers.

Default: false

Since version: 5.0.5

strictUpdates

Should the driver do strict checking (all primary keys selected) of updatable result sets (true, false, defaults to 'true')?

Default: true

Since version: 3.0.4

tinyInt1isBit

Should the driver treat the datatype TINYINT(1) as the BIT type (because the server silently converts BIT -> TINYINT(1) when creating tables)?

Default: true

Since version: 3.0.16

transformedBitIsBoolean

If the driver converts TINYINT(1) to a different type, should it use BOOLEAN instead of BIT for future compatibility with MySQL-5.0, as MySQL-5.0 has a BIT type?

Default: false

Since version: 3.1.9

Metadata. 

Properties and Descriptions

getProceduresReturnsFunctions

Pre-JDBC4 DatabaseMetaData API has only the getProcedures() and getProcedureColumns() methods, so they return metadata info for both stored procedures and functions. JDBC4 was extended with the getFunctions() and getFunctionColumns() methods and the expected behaviours of previous methods are not well defined. For JDBC4 and higher, default 'true' value of the option means that calls of DatabaseMetaData.getProcedures() and DatabaseMetaData.getProcedureColumns() return metadata for both procedures and functions as before, keeping backward compatibility. Setting this property to 'false' decouples Connector/J from its pre-JDBC4 behaviours for DatabaseMetaData.getProcedures() and DatabaseMetaData.getProcedureColumns(), forcing them to return metadata for procedures only.

Default: true

Since version: 5.1.26

noAccessToProcedureBodies

When determining procedure parameter types for CallableStatements, and the connected user can't access procedure bodies through "SHOW CREATE PROCEDURE" or select on mysql.proc should the driver instead create basic metadata (all parameters reported as INOUT VARCHARs) instead of throwing an exception?

Default: false

Since version: 5.0.3

nullCatalogMeansCurrent

When DatabaseMetadataMethods ask for a 'catalog' parameter, does the value null mean use the current catalog? (this is not JDBC-compliant, but follows legacy behavior from earlier versions of the driver)

Default: false

Since version: 3.1.8

nullNamePatternMatchesAll

Should DatabaseMetaData methods that accept *pattern parameters treat null the same as '%' (this is not JDBC-compliant, however older versions of the driver accepted this departure from the specification)

Default: false

Since version: 3.1.8

useHostsInPrivileges

Add '@hostname' to users in DatabaseMetaData.getColumn/TablePrivileges() (true/false), defaults to 'true'.

Default: true

Since version: 3.0.2

useInformationSchema

When connected to MySQL-5.0.7 or newer, should the driver use the INFORMATION_SCHEMA to derive information used by DatabaseMetaData?

Default: false

Since version: 5.0.0

BLOB/CLOB processing. 

Properties and Descriptions

autoDeserialize

Should the driver automatically detect and de-serialize objects stored in BLOB fields?

Default: false

Since version: 3.1.5

blobSendChunkSize

Chunk size to use when sending BLOB/CLOBs via ServerPreparedStatements. Note that this value cannot exceed the value of "maxAllowedPacket" and, if that is the case, then this value will be corrected automatically.

Default: 1048576

Since version: 3.1.9

blobsAreStrings

Should the driver always treat BLOBs as Strings - specifically to work around dubious metadata returned by the server for GROUP BY clauses?

Default: false

Since version: 5.0.8

clobCharacterEncoding

The character encoding to use for sending and retrieving TEXT, MEDIUMTEXT and LONGTEXT values instead of the configured connection characterEncoding

Since version: 5.0.0

emulateLocators

Should the driver emulate java.sql.Blobs with locators? With this feature enabled, the driver will delay loading the actual Blob data until the one of the retrieval methods (getInputStream(), getBytes(), and so forth) on the blob data stream has been accessed. For this to work, you must use a column alias with the value of the column to the actual name of the Blob. The feature also has the following restrictions: The SELECT that created the result set must reference only one table, the table must have a primary key; the SELECT must alias the original blob column name, specified as a string, to an alternate name; the SELECT must cover all columns that make up the primary key.

Default: false

Since version: 3.1.0

functionsNeverReturnBlobs

Should the driver always treat data from functions returning BLOBs as Strings - specifically to work around dubious metadata returned by the server for GROUP BY clauses?

Default: false

Since version: 5.0.8

locatorFetchBufferSize

If 'emulateLocators' is configured to 'true', what size buffer should be used when fetching BLOB data for getBinaryInputStream?

Default: 1048576

Since version: 3.2.1

Datetime types processing. 

Properties and Descriptions

noDatetimeStringSync

Don't ensure that ResultSet.getDatetimeType().toString().equals(ResultSet.getString())

Default: false

Since version: 3.1.7

sendFractionalSeconds

Send fractional part from TIMESTAMP seconds. If set to false, the nanoseconds value of TIMESTAMP values will be truncated before sending any data to the server. This option applies only to prepared statements, callable statements or updatable result sets.

Default: true

Since version: 5.1.37

serverTimezone

Override detection/mapping of time zone. Used when time zone from server doesn't map to Java time zone

Since version: 3.0.2

treatUtilDateAsTimestamp

Should the driver treat java.util.Date as a TIMESTAMP for the purposes of PreparedStatement.setObject()?

Default: true

Since version: 5.0.5

yearIsDateType

Should the JDBC driver treat the MySQL type "YEAR" as a java.sql.Date, or as a SHORT?

Default: true

Since version: 3.1.9

zeroDateTimeBehavior

What should happen when the driver encounters DATETIME values that are composed entirely of zeros (used by MySQL to represent invalid dates)? Valid values are "exception", "round" and "convertToNull".

Default: exception

Since version: 3.1.4

High Availability and Clustering. 

Properties and Descriptions

autoReconnect

Should the driver try to re-establish stale and/or dead connections? If enabled the driver will throw an exception for a queries issued on a stale or dead connection, which belong to the current transaction, but will attempt reconnect before the next query issued on the connection in a new transaction. The use of this feature is not recommended, because it has side effects related to session state and data consistency when applications don't handle SQLExceptions properly, and is only designed to be used when you are unable to configure your application to handle SQLExceptions resulting from dead and stale connections properly. Alternatively, as a last option, investigate setting the MySQL server variable "wait_timeout" to a high value, rather than the default of 8 hours.

Default: false

Since version: 1.1

autoReconnectForPools

Use a reconnection strategy appropriate for connection pools (defaults to 'false')

Default: false

Since version: 3.1.3

failOverReadOnly

When failing over in autoReconnect mode, should the connection be set to 'read-only'?

Default: true

Since version: 3.0.12

maxReconnects

Maximum number of reconnects to attempt if autoReconnect is true, default is '3'.

Default: 3

Since version: 1.1

reconnectAtTxEnd

If autoReconnect is set to true, should the driver attempt reconnections at the end of every transaction?

Default: false

Since version: 3.0.10

retriesAllDown

When using loadbalancing or failover, the number of times the driver should cycle through available hosts, attempting to connect. Between cycles, the driver will pause for 250ms if no servers are available.

Default: 120

Since version: 5.1.6

initialTimeout

If autoReconnect is enabled, the initial time to wait between re-connect attempts (in seconds, defaults to '2').

Default: 2

Since version: 1.1

queriesBeforeRetryMaster

Number of queries to issue before falling back to the primary host when failed over (when using multi-host failover). Whichever condition is met first, 'queriesBeforeRetryMaster' or 'secondsBeforeRetryMaster' will cause an attempt to be made to reconnect to the primary host. Setting both properties to 0 disables the automatic fall back to the primary host at transaction boundaries. Defaults to 50.

Default: 50

Since version: 3.0.2

secondsBeforeRetryMaster

How long should the driver wait, when failed over, before attempting to reconnect to the primary host? Whichever condition is met first, 'queriesBeforeRetryMaster' or 'secondsBeforeRetryMaster' will cause an attempt to be made to reconnect to the master. Setting both properties to 0 disables the automatic fall back to the primary host at transaction boundaries. Time in seconds, defaults to 30

Default: 30

Since version: 3.0.2

allowMasterDownConnections

By default, a replication-aware connection will fail to connect when configured master hosts are all unavailable at initial connection. Setting this property to 'true' allows to establish the initial connection, by failing over to the slave servers, in read-only state. It won't prevent subsequent failures when switching back to the master hosts i.e. by setting the replication connection to read/write state.

Default: false

Since version: 5.1.27

allowSlaveDownConnections

By default, a replication-aware connection will fail to connect when configured slave hosts are all unavailable at initial connection. Setting this property to 'true' allows to establish the initial connection. It won't prevent failures when switching to slaves i.e. by setting the replication connection to read-only state. The property 'readFromMasterWhenNoSlaves' should be used for this purpose.

Default: false

Since version: 5.1.38

ha.enableJMX

Enables JMX-based management of load-balanced connection groups, including live addition/removal of hosts from load-balancing pool. Enables JMX-based management of replication connection groups, including live slave promotion, addition of new slaves and removal of master or slave hosts from load-balanced master and slave connection pools.

Default: false

Since version: 5.1.27

loadBalanceHostRemovalGracePeriod

Sets the grace period to wait for a host being removed from a load-balanced connection, to be released when it is currently the active host.

Default: 15000

Since version: 5.1.39

readFromMasterWhenNoSlaves

Replication-aware connections distribute load by using the master hosts when in read/write state and by using the slave hosts when in read-only state. If, when setting the connection to read-only state, none of the slave hosts are available, an SQLExeception is thrown back. Setting this property to 'true' allows to fail over to the master hosts, while setting the connection state to read-only, when no slave hosts are available at switch instant.

Default: false

Since version: 5.1.38

selfDestructOnPingMaxOperations

=If set to a non-zero value, the driver will report close the connection and report failure when Connection.ping() or Connection.isValid(int) is called if the connection's count of commands sent to the server exceeds this value.

Default: 0

Since version: 5.1.6

selfDestructOnPingSecondsLifetime

If set to a non-zero value, the driver will report close the connection and report failure when Connection.ping() or Connection.isValid(int) is called if the connection's lifetime exceeds this value.

Default: 0

Since version: 5.1.6

ha.loadBalanceStrategy

If using a load-balanced connection to connect to SQL nodes in a MySQL Cluster/NDB configuration (by using the URL prefix "jdbc:mysql:loadbalance://"), which load balancing algorithm should the driver use: (1) "random" - the driver will pick a random host for each request. This tends to work better than round-robin, as the randomness will somewhat account for spreading loads where requests vary in response time, while round-robin can sometimes lead to overloaded nodes if there are variations in response times across the workload. (2) "bestResponseTime" - the driver will route the request to the host that had the best response time for the previous transaction.

Default: random

Since version: 5.0.6

loadBalanceAutoCommitStatementRegex

When load-balancing is enabled for auto-commit statements (via loadBalanceAutoCommitStatementThreshold), the statement counter will only increment when the SQL matches the regular expression. By default, every statement issued matches.

Since version: 5.1.15

loadBalanceAutoCommitStatementThreshold

When auto-commit is enabled, the number of statements which should be executed before triggering load-balancing to rebalance. Default value of 0 causes load-balanced connections to only rebalance when exceptions are encountered, or auto-commit is disabled and transactions are explicitly committed or rolled back.

Default: 0

Since version: 5.1.15

loadBalanceBlacklistTimeout

Time in milliseconds between checks of servers which are unavailable, by controlling how long a server lives in the global blacklist.

Default: 0

Since version: 5.1.0

loadBalanceConnectionGroup

Logical group of load-balanced connections within a classloader, used to manage different groups independently. If not specified, live management of load-balanced connections is disabled.

Since version: 5.1.13

loadBalanceExceptionChecker

Fully-qualified class name of custom exception checker. The class must implement com.mysql.cj.api.jdbc.ha.LoadBalanceExceptionChecker interface, and is used to inspect SQLExceptions and determine whether they should trigger fail-over to another host in a load-balanced deployment.

Default: com.mysql.cj.jdbc.ha.StandardLoadBalanceExceptionChecker

Since version: 5.1.13

loadBalancePingTimeout

Time in milliseconds to wait for ping response from each of load-balanced physical connections when using load-balanced Connection.

Default: 0

Since version: 5.1.13

loadBalanceSQLExceptionSubclassFailover

Comma-delimited list of classes/interfaces used by default load-balanced exception checker to determine whether a given SQLException should trigger failover. The comparison is done using Class.isInstance(SQLException) using the thrown SQLException.

Since version: 5.1.13

loadBalanceSQLStateFailover

Comma-delimited list of SQLState codes used by default load-balanced exception checker to determine whether a given SQLException should trigger failover. The SQLState of a given SQLException is evaluated to determine whether it begins with any value in the comma-delimited list.

Since version: 5.1.13

loadBalanceValidateConnectionOnSwapServer

Should the load-balanced Connection explicitly check whether the connection is live when swapping to a new physical connection at commit/rollback?

Default: false

Since version: 5.1.13

pinGlobalTxToPhysicalConnection

When using XAConnections, should the driver ensure that operations on a given XID are always routed to the same physical connection? This allows the XAConnection to support "XA START ... JOIN" after "XA END" has been called

Default: false

Since version: 5.0.1

resourceId

A globally unique name that identifies the resource that this datasource or connection is connected to, used for XAResource.isSameRM() when the driver can't determine this value based on hostnames used in the URL

Since version: 5.0.1

Performance Extensions. 

Properties and Descriptions

callableStmtCacheSize

If 'cacheCallableStmts' is enabled, how many callable statements should be cached?

Default: 100

Since version: 3.1.2

metadataCacheSize

The number of queries to cache ResultSetMetadata for if cacheResultSetMetaData is set to 'true' (default 50)

Default: 50

Since version: 3.1.1

useLocalSessionState

Should the driver refer to the internal values of autocommit and transaction isolation that are set by Connection.setAutoCommit() and Connection.setTransactionIsolation() and transaction state as maintained by the protocol, rather than querying the database or blindly sending commands to the database for commit() or rollback() method calls?

Default: false

Since version: 3.1.7

useLocalTransactionState

Should the driver use the in-transaction state provided by the MySQL protocol to determine if a commit() or rollback() should actually be sent to the database?

Default: false

Since version: 5.1.7

prepStmtCacheSize

If prepared statement caching is enabled, how many prepared statements should be cached?

Default: 25

Since version: 3.0.10

prepStmtCacheSqlLimit

If prepared statement caching is enabled, what's the largest SQL the driver will cache the parsing for?

Default: 256

Since version: 3.0.10

parseInfoCacheFactory

Name of a class implementing com.mysql.cj.api.CacheAdapterFactory, which will be used to create caches for the parsed representation of client-side prepared statements.

Default: com.mysql.cj.jdbc.util.PerConnectionLRUFactory

Since version: 5.1.1

serverConfigCacheFactory

Name of a class implementing com.mysql.cj.api.CacheAdapterFactory<String, Map<String, String>>, which will be used to create caches for MySQL server configuration values

Default: com.mysql.cj.core.util.PerVmServerConfigCacheFactory

Since version: 5.1.1

alwaysSendSetIsolation

Should the driver always communicate with the database when Connection.setTransactionIsolation() is called? If set to false, the driver will only communicate with the database when the requested transaction isolation is different than the whichever is newer, the last value that was set via Connection.setTransactionIsolation(), or the value that was read from the server when the connection was established. Note that useLocalSessionState=true will force the same behavior as alwaysSendSetIsolation=false, regardless of how alwaysSendSetIsolation is set.

Default: true

Since version: 3.1.7

maintainTimeStats

Should the driver maintain various internal timers to enable idle time calculations as well as more verbose error messages when the connection to the server fails? Setting this property to false removes at least two calls to System.getCurrentTimeMillis() per query.

Default: true

Since version: 3.1.9

useCursorFetch

If connected to MySQL > 5.0.2, and setFetchSize() > 0 on a statement, should that statement use cursor-based fetching to retrieve rows?

Default: false

Since version: 5.0.0

cacheCallableStmts

Should the driver cache the parsing stage of CallableStatements

Default: false

Since version: 3.1.2

cachePrepStmts

Should the driver cache the parsing stage of PreparedStatements of client-side prepared statements, the "check" for suitability of server-side prepared and server-side prepared statements themselves?

Default: false

Since version: 3.0.10

cacheResultSetMetadata

Should the driver cache ResultSetMetaData for Statements and PreparedStatements? (Req. JDK-1.4+, true/false, default 'false')

Default: false

Since version: 3.1.1

cacheServerConfiguration

Should the driver cache the results of 'SHOW VARIABLES' and 'SHOW COLLATION' on a per-URL basis?

Default: false

Since version: 3.1.5

defaultFetchSize

The driver will call setFetchSize(n) with this value on all newly-created Statements

Default: 0

Since version: 3.1.9

dontCheckOnDuplicateKeyUpdateInSQL

Stops checking if every INSERT statement contains the "ON DUPLICATE KEY UPDATE" clause. As a side effect, obtaining the statement's generated keys information will return a list where normally it wouldn't. Also be aware that, in this case, the list of generated keys returned may not be accurate. The effect of this property is canceled if set simultaneously with 'rewriteBatchedStatements=true'.

Default: false

Since version: 5.1.32

elideSetAutoCommits

If using MySQL-4.1 or newer, should the driver only issue 'set autocommit=n' queries when the server's state doesn't match the requested state by Connection.setAutoCommit(boolean)?

Default: false

Since version: 3.1.3

enableEscapeProcessing

Sets the default escape processing behavior for Statement objects. The method Statement.setEscapeProcessing() can be used to specify the escape processing behavior for an individual Statement object. Default escape processing behavior in prepared statements must be defined with the property 'processEscapeCodesForPrepStmts'.

Default: true

Since version: 5.1.37

enableQueryTimeouts

When enabled, query timeouts set via Statement.setQueryTimeout() use a shared java.util.Timer instance for scheduling. Even if the timeout doesn't expire before the query is processed, there will be memory used by the TimerTask for the given timeout which won't be reclaimed until the time the timeout would have expired if it hadn't been cancelled by the driver. High-load environments might want to consider disabling this functionality.

Default: true

Since version: 5.0.6

largeRowSizeThreshold

What size result set row should the JDBC driver consider "large", and thus use a more memory-efficient way of representing the row internally?

Default: 2048

Since version: 5.1.1

readOnlyPropagatesToServer

Should the driver issue appropriate statements to implicitly set the transaction access mode on server side when Connection.setReadOnly() is called? Setting this property to 'true' enables InnoDB read-only potential optimizations but also requires an extra roundtrip to set the right transaction state. Even if this property is set to 'false', the driver will do its best effort to prevent the execution of database-state-changing queries. Requires minimum of MySQL 5.6.

Default: true

Since version: 5.1.35

rewriteBatchedStatements

Should the driver use multiqueries (irregardless of the setting of "allowMultiQueries") as well as rewriting of prepared statements for INSERT into multi-value inserts when executeBatch() is called? Notice that this has the potential for SQL injection if using plain java.sql.Statements and your code doesn't sanitize input correctly. Notice that for prepared statements, server-side prepared statements can not currently take advantage of this rewrite option, and that if you don't specify stream lengths when using PreparedStatement.set*Stream(), the driver won't be able to determine the optimum number of parameters per batch and you might receive an error from the driver that the resultant packet is too large. Statement.getGeneratedKeys() for these rewritten statements only works when the entire batch includes INSERT statements. Please be aware using rewriteBatchedStatements=true with INSERT .. ON DUPLICATE KEY UPDATE that for rewritten statement server returns only one value as sum of all affected (or found) rows in batch and it isn't possible to map it correctly to initial statements; in this case driver returns 0 as a result of each batch statement if total count was 0, and the Statement.SUCCESS_NO_INFO as a result of each batch statement if total count was > 0.

Default: false

Since version: 3.1.13

useReadAheadInput

Use newer, optimized non-blocking, buffered input stream when reading from the server?

Default: true

Since version: 3.1.5

Debugging/Profiling. 

Properties and Descriptions

logger

The name of a class that implements "com.mysql.cj.api.log.Log" that will be used to log messages to. (default is "com.mysql.cj.core.log.StandardLogger", which logs to STDERR)

Default: com.mysql.cj.core.log.StandardLogger

Since version: 3.1.1

gatherPerfMetrics

Should the driver gather performance metrics, and report them via the configured logger every 'reportMetricsIntervalMillis' milliseconds?

Default: false

Since version: 3.1.2

profileSQL

Trace queries and their execution/fetch times to the configured logger (true/false) defaults to 'false'

Default: false

Since version: 3.1.0

reportMetricsIntervalMillis

If 'gatherPerfMetrics' is enabled, how often should they be logged (in ms)?

Default: 30000

Since version: 3.1.2

maxQuerySizeToLog

Controls the maximum length/size of a query that will get logged when profiling or tracing

Default: 2048

Since version: 3.1.3

packetDebugBufferSize

The maximum number of packets to retain when 'enablePacketDebug' is true

Default: 20

Since version: 3.1.3

slowQueryThresholdMillis

If 'logSlowQueries' is enabled, how long should a query (in ms) before it is logged as 'slow'?

Default: 2000

Since version: 3.1.2

slowQueryThresholdNanos

If 'useNanosForElapsedTime' is set to true, and this property is set to a non-zero value, the driver will use this threshold (in nanosecond units) to determine if a query was slow.

Default: 0

Since version: 5.0.7

useUsageAdvisor

Should the driver issue 'usage' warnings advising proper and efficient usage of JDBC and MySQL Connector/J to the log (true/false, defaults to 'false')?

Default: false

Since version: 3.1.1

autoGenerateTestcaseScript

Should the driver dump the SQL it is executing, including server-side prepared statements to STDERR?

Default: false

Since version: 3.1.9

autoSlowLog

Instead of using slowQueryThreshold* to determine if a query is slow enough to be logged, maintain statistics that allow the driver to determine queries that are outside the 99th percentile?

Default: true

Since version: 5.1.4

clientInfoProvider

The name of a class that implements the com.mysql.cj.api.jdbc.ClientInfoProvider interface in order to support JDBC-4.0's Connection.get/setClientInfo() methods

Default: com.mysql.cj.jdbc.CommentClientInfoProvider

Since version: 5.1.0

enablePacketDebug

When enabled, a ring-buffer of 'packetDebugBufferSize' packets will be kept, and dumped when exceptions are thrown in key areas in the driver's code

Default: false

Since version: 3.1.3

explainSlowQueries

If 'logSlowQueries' is enabled, should the driver automatically issue an 'EXPLAIN' on the server and send the results to the configured log at a WARN level?

Default: false

Since version: 3.1.2

logSlowQueries

Should queries that take longer than 'slowQueryThresholdMillis' be logged?

Default: false

Since version: 3.1.2

logXaCommands

Should the driver log XA commands sent by MysqlXaConnection to the server, at the DEBUG level of logging?

Default: false

Since version: 5.0.5

profilerEventHandler

Name of a class that implements the interface com.mysql.cj.api.ProfilerEventHandler that will be used to handle profiling/tracing events.

Default: com.mysql.cj.core.profiler.LoggingProfilerEventHandler

Since version: 5.1.6

resultSetSizeThreshold

If the usage advisor is enabled, how many rows should a result set contain before the driver warns that it is suspiciously large?

Default: 100

Since version: 5.0.5

traceProtocol

Should trace-level network protocol be logged?

Default: false

Since version: 3.1.2

useNanosForElapsedTime

For profiling/debugging functionality that measures elapsed time, should the driver try to use nanoseconds resolution if available (JDK >= 1.5)?

Default: false

Since version: 5.0.7

useOnlyServerErrorMessages

Don't prepend 'standard' SQLState error messages to error messages returned by the server.

Default: true

Since version: 3.0.15

Exceptions/Warnings. 

Properties and Descriptions

dumpQueriesOnException

Should the driver dump the contents of the query sent to the server in the message for SQLExceptions?

Default: false

Since version: 3.1.3

exceptionInterceptors

Comma-delimited list of classes that implement com.mysql.cj.api.exceptions.ExceptionInterceptor. These classes will be instantiated one per Connection instance, and all SQLExceptions thrown by the driver will be allowed to be intercepted by these interceptors, in a chained fashion, with the first class listed as the head of the chain.

Since version: 5.1.8

ignoreNonTxTables

Ignore non-transactional table warning for rollback? (defaults to 'false').

Default: false

Since version: 3.0.9

includeInnodbStatusInDeadlockExceptions

Include the output of "SHOW ENGINE INNODB STATUS" in exception messages when deadlock exceptions are detected?

Default: false

Since version: 5.0.7

includeThreadDumpInDeadlockExceptions

Include a current Java thread dump in exception messages when deadlock exceptions are detected?

Default: false

Since version: 5.1.15

includeThreadNamesAsStatementComment

Include the name of the current thread as a comment visible in "SHOW PROCESSLIST", or in Innodb deadlock dumps, useful in correlation with "includeInnodbStatusInDeadlockExceptions=true" and "includeThreadDumpInDeadlockExceptions=true".

Default: false

Since version: 5.1.15

Tunes for integration with other products. 

Properties and Descriptions

overrideSupportsIntegrityEnhancementFacility

Should the driver return "true" for DatabaseMetaData.supportsIntegrityEnhancementFacility() even if the database doesn't support it to workaround applications that require this method to return "true" to signal support of foreign keys, even though the SQL specification states that this facility contains much more than just foreign key support (one such application being OpenOffice)?

Default: false

Since version: 3.1.12

ultraDevHack

Create PreparedStatements for prepareCall() when required, because UltraDev is broken and issues a prepareCall() for _all_ statements? (true/false, defaults to 'false')

Default: false

Since version: 2.0.3

JDBC compliance. 

Properties and Descriptions

useColumnNamesInFindColumn

Prior to JDBC-4.0, the JDBC specification had a bug related to what could be given as a "column name" to ResultSet methods like findColumn(), or getters that took a String property. JDBC-4.0 clarified "column name" to mean the label, as given in an "AS" clause and returned by ResultSetMetaData.getColumnLabel(), and if no AS clause, the column name. Setting this property to "true" will give behavior that is congruent to JDBC-3.0 and earlier versions of the JDBC specification, but which because of the specification bug could give unexpected results. This property is preferred over "useOldAliasMetadataBehavior" unless you need the specific behavior that it provides with respect to ResultSetMetadata.

Default: false

Since version: 5.1.7

pedantic

Follow the JDBC spec to the letter.

Default: false

Since version: 3.0.0

useOldAliasMetadataBehavior

Should the driver use the legacy behavior for "AS" clauses on columns and tables, and only return aliases (if any) for ResultSetMetaData.getColumnName() or ResultSetMetaData.getTableName() rather than the original column/table name? In 5.0.x, the default value was true.

Default: false

Since version: 5.0.4

Fabric. 

Properties and Descriptions

fabricPassword

Fabric password

Since version: 5.1.30

fabricProtocol

Fabric protocol

Default: http

Since version: 5.1.30

fabricReportErrors

Fabric report errors

Default: false

Since version: 5.1.30

fabricServerGroup

Fabric server group

Since version: 5.1.30

fabricShardKey

Fabric shard key

Since version: 5.1.30

fabricShardTable

Fabric shard table

Since version: 5.1.30

fabricUsername

Fabric username

Since version: 5.1.30

X Protocol and X DevAPI. 

Properties and Descriptions

mysqlx.useAsyncProtocol

Use asynchronous variant of X Protocol

Default: true

Since version: 6.0.0

Connector/J also supports access to MySQL using named pipes on Windows platforms with the NamedPipeSocketFactory as a plugin-socket factory. If you do not use a namedPipePath property, the default of '\\.\pipe\MySQL' is used. If you use the NamedPipeSocketFactory, the host name and port number values in the JDBC URL are ignored. To enable this feature, set the socketFactory property:

socketFactory=com.mysql.cj.jdbc.NamedPipeSocketFactory

Named pipes only work when connecting to a MySQL server on the same physical machine where the JDBC driver is running. In simple performance tests, named pipe access is between 30%-50% faster than the standard TCP/IP access. However, this varies per system, and named pipes are slower than TCP/IP in many Windows configurations.

To create your own socket factories, follow the example code in com.mysql.cj.core.io.NamedPipeSocketFactory, or com.mysql.cj.core.io.StandardSocketFactory.

6.1.1 Properties Files for the useConfigs Option

The useConfigs connection option is convenient shorthand for specifying combinations of options for particular scenarios. The argument values you can use with this option correspond to the names of .properties files within the Connector/J mysql-connector-java-version-bin.jar JAR file. For example, the Connector/J 6.0.0 driver includes the following configuration properties files:

$ unzip mysql-connector-java-6.0.0-bin.jar '*/configs/*'
Archive:  mysql-connector-java-6.0.0-bin.jar
   creating: com/mysql/jdbc/configs/
  inflating: com/mysql/jdbc/configs/3-0-Compat.properties
  inflating: com/mysql/jdbc/configs/5-0-Compat.properties
  inflating: com/mysql/jdbc/configs/clusterBase.properties
  inflating: com/mysql/jdbc/configs/coldFusion.properties
  inflating: com/mysql/jdbc/configs/fullDebug.properties
  inflating: com/mysql/jdbc/configs/maxPerformance.properties
  inflating: com/mysql/jdbc/configs/solarisMaxPerformance.properties

To specify one of these combinations of options, specify useConfigs=3-0-Compat, useConfigs=maxPerformance, and so on. The following sections show the options that are part of each useConfigs setting. For the details of why each one is included, see the comments in the .properties files.

3-0-Compat

emptyStringsConvertToZero=true
jdbcCompliantTruncation=false
noDatetimeStringSync=true
nullCatalogMeansCurrent=true
nullNamePatternMatchesAll=true
transformedBitIsBoolean=false
dontTrackOpenResources=true
zeroDateTimeBehavior=convertToNull
useServerPrepStmts=false
autoClosePStmtStreams=true
processEscapeCodesForPrepStmts=false
useFastDateParsing=false
populateInsertRowWithDefaultValues=false
useDirectRowUnpack=false

5-0-Compat

useDirectRowUnpack=false

clusterBase

autoReconnect=true
failOverReadOnly=false
roundRobinLoadBalance=true

coldFusion

alwaysSendSetIsolation=false
useLocalSessionState=true
autoReconnect=true

fullDebug

profileSQL=true
gatherPerfMetrics=true
useUsageAdvisor=true
logSlowQueries=true
explainSlowQueries=true

maxPerformance

cachePrepStmts=true
cacheCallableStmts=true
cacheServerConfiguration=true
useLocalSessionState=true
elideSetAutoCommits=true
alwaysSendSetIsolation=false
enableQueryTimeouts=false

solarisMaxPerformance

useUnbufferedInput=false
useReadAheadInput=false
maintainTimeStats=false

6.2 JDBC API Implementation Notes

MySQL Connector/J, as a rigorous implementation of the JDBC API, passes all of the tests in the publicly available version of Oracle's JDBC compliance test suite. The JDBC specification is flexible on how certain functionality should be implemented. This section gives details on an interface-by-interface level about implementation decisions that might affect how you code applications with MySQL Connector/J.

BLOB

You can emulate BLOBs with locators by adding the property emulateLocators=true to your JDBC URL. Using this method, the driver will delay loading the actual BLOB data until you retrieve the other data and then use retrieval methods (getInputStream(), getBytes(), and so forth) on the BLOB data stream.

You must use a column alias with the value of the column to the actual name of the BLOB, for example:

SELECT id, 'data' as blob_data from blobtable

You must also follow these rules:

The SELECT must reference only one table. The table must have a primary key.

The SELECT must alias the original BLOB column name, specified as a string, to an alternate name.

The SELECT must cover all columns that make up the primary key.

The BLOB implementation does not allow in-place modification (they are copies, as reported by the DatabaseMetaData.locatorsUpdateCopies() method). Because of this, use the corresponding PreparedStatement.setBlob() or ResultSet.updateBlob() (in the case of updatable result sets) methods to save changes back to the database.

CallableStatement

Stored procedures are supported when connecting to MySQL using the CallableStatement interface. Currently, the getParameterMetaData() method of CallableStatement is not supported.

CLOB

The CLOB implementation does not allow in-place modification (they are copies, as reported by the DatabaseMetaData.locatorsUpdateCopies() method). Because of this, use the PreparedStatement.setClob() method to save changes back to the database. The JDBC API does not have a ResultSet.updateClob() method.

Connection

The isClosed() method does not ping the server to determine if it is available. In accordance with the JDBC specification, it only returns true if closed() has been called on the connection. If you need to determine if the connection is still valid, issue a simple query, such as SELECT 1. The driver will throw an exception if the connection is no longer valid.

DatabaseMetaData

Foreign key information (getImportedKeys()/getExportedKeys() and getCrossReference()) is only available from InnoDB tables. The driver uses SHOW CREATE TABLE to retrieve this information, so if any other storage engines add support for foreign keys, the driver would transparently support them as well.

PreparedStatement

PreparedStatements are implemented by the driver, as MySQL does not have a prepared statement feature. Because of this, the driver does not implement getParameterMetaData() or getMetaData() as it would require the driver to have a complete SQL parser in the client.

Server-side prepared statements and binary-encoded result sets are used when the server supports them. Be careful when using a server-side prepared statement with large parameters that are set using setBinaryStream(), setAsciiStream(), setUnicodeStream(), setBlob(), or setClob(). To re-execute the statement with any large parameter changed to a nonlarge parameter, call clearParameters() and set all parameters again. The reason for this is as follows:

During both server-side prepared statements and client-side emulation, large data is exchanged only when PreparedStatement.execute() is called.

Once that has been done, the stream used to read the data on the client side is closed (as per the JDBC spec), and cannot be read from again.

If a parameter changes from large to nonlarge, the driver must reset the server-side state of the prepared statement to allow the parameter that is being changed to take the place of the prior large value. This removes all of the large data that has already been sent to the server, thus requiring the data to be re-sent, using the setBinaryStream(), setAsciiStream(), setUnicodeStream(), setBlob() or setClob() method.

Consequently, to change the type of a parameter to a nonlarge one, you must call clearParameters() and set all parameters of the prepared statement again before it can be re-executed.

ResultSet

By default, ResultSets are completely retrieved and stored in memory. In most cases this is the most efficient way to operate and, due to the design of the MySQL network protocol, is easier to implement. If you are working with ResultSets that have a large number of rows or large values and cannot allocate heap space in your JVM for the memory required, you can tell the driver to stream the results back one row at a time.

To enable this functionality, create a Statement instance in the following manner:

stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
              java.sql.ResultSet.CONCUR_READ_ONLY);
stmt.setFetchSize(Integer.MIN_VALUE);

The combination of a forward-only, read-only result set, with a fetch size of Integer.MIN_VALUE serves as a signal to the driver to stream result sets row-by-row. After this, any result sets created with the statement will be retrieved row-by-row.

There are some caveats with this approach. You must read all of the rows in the result set (or close it) before you can issue any other queries on the connection, or an exception will be thrown.

The earliest the locks these statements hold can be released (whether they be MyISAM table-level locks or row-level locks in some other storage engine such as InnoDB) is when the statement completes.

If the statement is within scope of a transaction, then locks are released when the transaction completes (which implies that the statement needs to complete first). As with most other databases, statements are not complete until all the results pending on the statement are read or the active result set for the statement is closed.

Therefore, if using streaming results, process them as quickly as possible if you want to maintain concurrent access to the tables referenced by the statement producing the result set.

Statement

Connector/J includes support for both Statement.cancel() and Statement.setQueryTimeout(). Both require a separate connection to issue the KILL QUERY statement. In the case of setQueryTimeout(), the implementation creates an additional thread to handle the timeout functionality.

Note

Failures to cancel the statement for setQueryTimeout() may manifest themselves as RuntimeException rather than failing silently, as there is currently no way to unblock the thread that is executing the query being cancelled due to timeout expiration and have it throw the exception instead.

MySQL does not support SQL cursors, and the JDBC driver does not emulate them, so setCursorName() has no effect.

Connector/J also supplies two additional methods:

setLocalInfileInputStream() sets an InputStream instance that will be used to send data to the MySQL server for a LOAD DATA LOCAL INFILE statement rather than a FileInputStream or URLInputStream that represents the path given as an argument to the statement.

This stream will be read to completion upon execution of a LOAD DATA LOCAL INFILE statement, and will automatically be closed by the driver, so it needs to be reset before each call to execute*() that would cause the MySQL server to request data to fulfill the request for LOAD DATA LOCAL INFILE.

If this value is set to NULL, the driver will revert to using a FileInputStream or URLInputStream as required.

getLocalInfileInputStream() returns the InputStream instance that will be used to send data in response to a LOAD DATA LOCAL INFILE statement.

This method returns NULL if no such stream has been set using setLocalInfileInputStream().

6.3 Java, JDBC and MySQL Types

MySQL Connector/J is flexible in the way it handles conversions between MySQL data types and Java data types.

In general, any MySQL data type can be converted to a java.lang.String, and any numeric type can be converted to any of the Java numeric types, although round-off, overflow, or loss of precision may occur.

Note

All TEXT types return Types.LONGVARCHAR with different getPrecision() values (65535, 255, 16777215, and 2147483647 respectively) with getColumnType() returning -1. This behavior is intentional even though TINYTEXT does not fall, regarding to its size, within the LONGVARCHAR category. This is to avoid different handling inside the same base type. And getColumnType() returns -1 because the internal server handling is of type TEXT, which is similar to BLOB.

Also note that getColumnTypeName() will return VARCHAR even though getColumnType() returns Types.LONGVARCHAR, because VARCHAR is the designated column database-specific name for this type.

Connector/J issues warnings or throws DataTruncation exceptions as is required by the JDBC specification, unless the connection was configured not to do so by using the property jdbcCompliantTruncation and setting it to false.

The conversions that are always guaranteed to work are listed in the following table. The first column lists one or more MySQL data types, and the second column lists one or more Java types to which the MySQL types can be converted.

Table 6.1 Connection Properties - Miscellaneous

These MySQL Data Types | Can always be converted to these Java types
CHAR, VARCHAR, BLOB, TEXT, ENUM, and SET | java.lang.String, java.io.InputStream, java.io.Reader, java.sql.Blob, java.sql.Clob
FLOAT, REAL, DOUBLE PRECISION, NUMERIC, DECIMAL, TINYINT, SMALLINT, MEDIUMINT, INTEGER, BIGINT | java.lang.String, java.lang.Short, java.lang.Integer, java.lang.Long, java.lang.Double, java.math.BigDecimal
DATE, TIME, DATETIME, TIMESTAMP | java.lang.String, java.sql.Date, java.sql.Timestamp

Note

Round-off, overflow or loss of precision may occur if you choose a Java numeric data type that has less precision or capacity than the MySQL data type you are converting to/from.

The ResultSet.getObject() method uses the type conversions between MySQL and Java types, following the JDBC specification where appropriate. The value returned by ResultSetMetaData.GetColumnClassName() is also shown below. For more information on the JDBC types, see the reference on the java.sql.Types class.

Table 6.2 MySQL Types to Java Types for ResultSet.getObject()

MySQL Type Name | Return value of GetColumnClassName | Returned as Java Class
BIT(1) | BIT | java.lang.Boolean
BIT( > 1) | BIT | byte[]
TINYINT | TINYINT | java.lang.Boolean if the configuration property tinyInt1isBit is set to true (the default) and the storage size is 1, or java.lang.Integer if not.
BOOL, BOOLEAN | TINYINT | See TINYINT, above as these are aliases for TINYINT(1), currently.
SMALLINT[(M)] [UNSIGNED] | SMALLINT [UNSIGNED] | java.lang.Integer (regardless of whether it is UNSIGNED or not)
MEDIUMINT[(M)] [UNSIGNED] | MEDIUMINT [UNSIGNED] | java.lang.Integer (regardless of whether it is UNSIGNED or not)
INT,INTEGER[(M)] [UNSIGNED] | INTEGER [UNSIGNED] | java.lang.Integer, if UNSIGNED java.lang.Long
BIGINT[(M)] [UNSIGNED] | BIGINT [UNSIGNED] | java.lang.Long, if UNSIGNED java.math.BigInteger
FLOAT[(M,D)] | FLOAT | java.lang.Float
DOUBLE[(M,B)] | DOUBLE | java.lang.Double
DECIMAL[(M[,D])] | DECIMAL | java.math.BigDecimal
DATE | DATE | java.sql.Date
DATETIME | DATETIME | java.sql.Timestamp
TIMESTAMP[(M)] | TIMESTAMP | java.sql.Timestamp
TIME | TIME | java.sql.Time
YEAR[(2|4)] | YEAR | If yearIsDateType configuration property is set to false, then the returned object type is java.sql.Short. If set to true (the default), then the returned object is of type java.sql.Date with the date set to January 1st, at midnight.
CHAR(M) | CHAR | java.lang.String (unless the character set for the column is BINARY, then byte[] is returned.
VARCHAR(M) [BINARY] | VARCHAR | java.lang.String (unless the character set for the column is BINARY, then byte[] is returned.
BINARY(M) | BINARY | byte[]
VARBINARY(M) | VARBINARY | byte[]
TINYBLOB | TINYBLOB | byte[]
TINYTEXT | VARCHAR | java.lang.String
BLOB | BLOB | byte[]
TEXT | VARCHAR | java.lang.String
MEDIUMBLOB | MEDIUMBLOB | byte[]
MEDIUMTEXT | VARCHAR | java.lang.String
LONGBLOB | LONGBLOB | byte[]
LONGTEXT | VARCHAR | java.lang.String
ENUM('value1','value2',...) | CHAR | java.lang.String
SET('value1','value2',...) | CHAR | java.lang.String

6.4 Using Character Sets and Unicode

All strings sent from the JDBC driver to the server are converted automatically from native Java Unicode form to the client character encoding, including all queries sent using Statement.execute(), Statement.executeUpdate(), Statement.executeQuery() as well as all PreparedStatement and CallableStatement parameters with the exclusion of parameters set using setBytes(), setBinaryStream(), setAsciiStream(), setUnicodeStream() and setBlob().

Number of Encodings Per Connection

Connector/J supports a single character encoding between client and server, and any number of character encodings for data returned by the server to the client in the results.

Setting the Character Encoding

The character encoding between client and server is automatically detected upon connection. You specify the encoding on the server using the character_set_server. The driver automatically uses the encoding specified by the server. For more information, see Server Character Set and Collation.

For example, to use 4-byte UTF-8 character sets with Connector/J, configure the MySQL server with character_set_server=utf8mb4, and leave characterEncoding out of the Connector/J connection string. Connector/J will then autodetect the UTF-8 setting.

To override the automatically detected encoding on the client side, use the characterEncoding property in the URL used to connect to the server.

To allow multiple character sets to be sent from the client, use the UTF-8 encoding, either by configuring utf8 as the default server character set, or by configuring the JDBC driver to use UTF-8 through the characterEncoding property.

When specifying character encodings on the client side, use Java-style names. The following table lists MySQL character set names and the corresponding Java-style names:

Table 6.3 MySQL to Java Encoding Name Translations

MySQL Character Set Name | Java-Style Character Encoding Name
ascii | US-ASCII
big5 | Big5
gbk | GBK
sjis | SJIS or Cp932
cp932 | Cp932 or MS932
gb2312 | EUC_CN
ujis | EUC_JP
euckr | EUC_KR
latin1 | Cp1252
latin2 | ISO8859_2
greek | ISO8859_7
hebrew | ISO8859_8
cp866 | Cp866
tis620 | TIS620
cp1250 | Cp1250
cp1251 | Cp1251
cp1257 | Cp1257
macroman | MacRoman
macce | MacCentralEurope
utf8 | UTF-8
ucs2 | UnicodeBig

Warning

Do not issue the query set names with Connector/J, as the driver will not detect that the character set has changed, and will continue to use the character set detected during the initial connection setup.

6.5 Connecting Securely Using SSL

SSL in MySQL Connector/J encrypts all data (other than the initial handshake) between the JDBC driver and the server. There is a performance penalty for enabling SSL, the severity of which depends on multiple factors including (but not limited to) the size of the query, the amount of data returned, the server hardware, the SSL library used, the network bandwidth, and so on.

For SSL support to work, you must have the following:

A JRE that includes JSSE (Java Secure Sockets Extension), like JRE 1.8.

A MySQL server that supports SSL and has been compiled and configured to do so. For more information, see Building MySQL with Support for Secure Connections.

A client certificate (covered later in this section)

The system works through two Java truststore files, one file contains the certificate information for the server (truststore in the examples below). The other file contains the certificate for the client (keystore in the examples below). All Java truststore files are password protected by supplying a suitable password to the keytool when you create the files. You need the file names and associated passwords to create an SSL connection.

You will first need to import the MySQL server CA Certificate into a Java truststore. A sample MySQL server CA Certificate is located in the SSL subdirectory of the MySQL source distribution. This is what SSL will use to determine if you are communicating with a secure MySQL server. Alternatively, use the CA Certificate that you have generated or been provided with by your SSL provider.

To use Java's keytool to create a truststore in the current directory , and import the server's CA certificate (cacert.pem), you can do the following (assuming that keytool is in your path. The keytool is typically located in the bin subdirectory of your JDK or JRE):

shell> keytool -import -alias mysqlServerCACert \
         -file cacert.pem -keystore truststore

Enter the password when prompted for the keystore file. Interaction with keytool looks like this:

Enter keystore password:  *********
Owner: EMAILADDRESS=walrus@example.com, CN=Walrus,
       O=My Company, L=Orenburg, ST=Some-State, C=RU
Issuer: EMAILADDRESS=walrus@example.com, CN=Walrus,
       O=My Company, L=Orenburg, ST=Some-State, C=RU
Serial number: 0
Valid from:
   Fri Aug 02 16:55:53 CDT 2002 until: Sat Aug 02 16:55:53 CDT 2003
Certificate fingerprints:
    MD5:  61:91:A0:F2:03:07:61:7A:81:38:66:DA:19:C4:8D:AB
    SHA1: 25:77:41:05:D5:AD:99:8C:14:8C:CA:68:9C:2F:B8:89:C3:34:4D:6C
Trust this certificate? [no]:  yes
Certificate was added to keystore

You then have two options: either import the client certificate that matches the CA certificate you just imported, or create a new client certificate.

Importing an existing certificate requires the certificate to be in DER format. You can use openssl to convert an existing certificate into the new format. For example:

shell> openssl x509 -outform DER -in client-cert.pem -out client.cert

Now import the converted certificate into your keystore using keytool:

shell> keytool -import -file client.cert -keystore keystore -alias mysqlClientCertificate

To generate your own client certificate, use keytool to create a suitable certificate and add it to the keystore file:

shell> keytool -genkey -keyalg rsa \
     -alias mysqlClientCertificate -keystore keystore

Keytool will prompt you for the following information, and create a keystore named keystore in the current directory.

Respond with information that is appropriate for your situation:

Enter keystore password:  *********
What is your first and last name?
  [Unknown]:  Matthews
What is the name of your organizational unit?
  [Unknown]:  Software Development
What is the name of your organization?
  [Unknown]:  My Company
What is the name of your City or Locality?
  [Unknown]:  Flossmoor
What is the name of your State or Province?
  [Unknown]:  IL
What is the two-letter country code for this unit?
  [Unknown]:  US
Is <CN=Matthews, OU=Software Development, O=My Company,
 L=Flossmoor, ST=IL, C=US> correct?
  [no]:  y

Enter key password for <mysqlClientCertificate>
        (RETURN if same as keystore password):

Finally, to get JSSE to use the keystore and truststore that you have generated, you need to set the following system properties when you start your JVM, replacing path_to_keystore_file with the full path to the keystore file you created, path_to_truststore_file with the path to the truststore file you created, and using the appropriate password values for each property. You can do this either on the command line:

-Djavax.net.ssl.keyStore=path_to_keystore_file
-Djavax.net.ssl.keyStorePassword=password
-Djavax.net.ssl.trustStore=path_to_truststore_file
-Djavax.net.ssl.trustStorePassword=password

Or you can set the values directly within the application:

System.setProperty("javax.net.ssl.keyStore","path_to_keystore_file");
System.setProperty("javax.net.ssl.keyStorePassword","password");
System.setProperty("javax.net.ssl.trustStore","path_to_truststore_file");
System.setProperty("javax.net.ssl.trustStorePassword","password");

You will also need to set useSSL to true in your connection parameters for MySQL Connector/J, either by adding useSSL=true to your URL, or by setting the property useSSL to true in the java.util.Properties instance you pass to DriverManager.getConnection().

You can test that SSL is working by turning on JSSE debugging (as detailed below), and look for the following key events:

...
*** ClientHello, v3.1
RandomCookie:  GMT: 1018531834 bytes = { 199, 148, 180, 215, 74, 12, »
  54, 244, 0, 168, 55, 103, 215, 64, 16, 138, 225, 190, 132, 153, 2, »
  217, 219, 239, 202, 19, 121, 78 }
Session ID:  {}
Cipher Suites:  { 0, 5, 0, 4, 0, 9, 0, 10, 0, 18, 0, 19, 0, 3, 0, 17 }
Compression Methods:  { 0 }
***
[write] MD5 and SHA1 hashes:  len = 59
0000: 01 00 00 37 03 01 3D B6 90 FA C7 94 B4 D7 4A 0C  ...7..=.......J.
0010: 36 F4 00 A8 37 67 D7 40 10 8A E1 BE 84 99 02 D9  6...7g.@........
0020: DB EF CA 13 79 4E 00 00 10 00 05 00 04 00 09 00  ....yN..........
0030: 0A 00 12 00 13 00 03 00 11 01 00                 ...........
main, WRITE:  SSL v3.1 Handshake, length = 59
main, READ:  SSL v3.1 Handshake, length = 74
*** ServerHello, v3.1
RandomCookie:  GMT: 1018577560 bytes = { 116, 50, 4, 103, 25, 100, 58, »
   202, 79, 185, 178, 100, 215, 66, 254, 21, 83, 187, 190, 42, 170, 3, »
   132, 110, 82, 148, 160, 92 }
Session ID:  {163, 227, 84, 53, 81, 127, 252, 254, 178, 179, 68, 63, »
   182, 158, 30, 11, 150, 79, 170, 76, 255, 92, 15, 226, 24, 17, 177, »
   219, 158, 177, 187, 143}
Cipher Suite:  { 0, 5 }
Compression Method: 0
***
%% Created:  [Session-1, SSL_RSA_WITH_RC4_128_SHA]
** SSL_RSA_WITH_RC4_128_SHA
[read] MD5 and SHA1 hashes:  len = 74
0000: 02 00 00 46 03 01 3D B6 43 98 74 32 04 67 19 64  ...F..=.C.t2.g.d
0010: 3A CA 4F B9 B2 64 D7 42 FE 15 53 BB BE 2A AA 03  :.O..d.B..S..*..
0020: 84 6E 52 94 A0 5C 20 A3 E3 54 35 51 7F FC FE B2  .nR..\ ..T5Q....
0030: B3 44 3F B6 9E 1E 0B 96 4F AA 4C FF 5C 0F E2 18  .D?.....O.L.\...
0040: 11 B1 DB 9E B1 BB 8F 00 05 00                    ..........
main, READ:  SSL v3.1 Handshake, length = 1712
...

JSSE provides debugging (to stdout) when you set the following system property: -Djavax.net.debug=all This will tell you what keystores and truststores are being used, as well as what is going on during the SSL handshake and certificate exchange. It will be helpful when trying to determine what is not working when trying to get an SSL connection to happen.

6.6 Connecting Using PAM Authentication

Java applications using Connector/J can connect to MySQL servers that use the pluggable authentication module (PAM) authentication scheme.

For PAM authentication to work, you must have the following:

A MySQL server that supports PAM authentication. See The PAM Authentication Plugin for more information. Connector/J implements the same cleartext authentication method as in The Cleartext Client-Side Authentication Plugin.

SSL capability, as explained in Section 6.5, “Connecting Securely Using SSL”. Because the PAM authentication scheme sends the original password to the server, the connection to the server must be encrypted.

PAM authentication support is enabled by default in Connector/J 6.0, so no extra configuration is needed.

To disable the PAM authentication feature, specify mysql_clear_password (the method) or com.mysql.cj.jdbc.authentication.MysqlClearPasswordPlugin (the class name) in the comma-separated list of arguments for the disabledAuthenticationPlugins connection option. See Section 6.1, “Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J” for details about that connection option.

6.7 Using Master/Slave Replication with ReplicationConnection

See Section 9.3, “Configuring Master/Slave Replication with Connector/J” for details on the topic.

6.8 Mapping MySQL Error Numbers to JDBC SQLState Codes

The table below provides a mapping of the MySQL error numbers to JDBC SQLState values.

Table 6.4 Mapping of MySQL Error Numbers to SQLStates

MySQL Error Number | MySQL Error Name | SQL Standard SQLState
1022 | ER_DUP_KEY | 23000
1037 | ER_OUTOFMEMORY | HY001
1038 | ER_OUT_OF_SORTMEMORY | HY001
1040 | ER_CON_COUNT_ERROR | 08004
1042 | ER_BAD_HOST_ERROR | 08S01
1043 | ER_HANDSHAKE_ERROR | 08S01
1044 | ER_DBACCESS_DENIED_ERROR | 42000
1045 | ER_ACCESS_DENIED_ERROR | 28000
1046 | ER_NO_DB_ERROR | 3D000
1047 | ER_UNKNOWN_COM_ERROR | 08S01
1048 | ER_BAD_NULL_ERROR | 23000
1049 | ER_BAD_DB_ERROR | 42000
1050 | ER_TABLE_EXISTS_ERROR | 42S01
1051 | ER_BAD_TABLE_ERROR | 42S02
1052 | ER_NON_UNIQ_ERROR | 23000
1053 | ER_SERVER_SHUTDOWN | 08S01
1054 | ER_BAD_FIELD_ERROR | 42S22
1055 | ER_WRONG_FIELD_WITH_GROUP | 42000
1056 | ER_WRONG_GROUP_FIELD | 42000
1057 | ER_WRONG_SUM_SELECT | 42000
1058 | ER_WRONG_VALUE_COUNT | 21S01
1059 | ER_TOO_LONG_IDENT | 42000
1060 | ER_DUP_FIELDNAME | 42S21
1061 | ER_DUP_KEYNAME | 42000
1062 | ER_DUP_ENTRY | 23000
1063 | ER_WRONG_FIELD_SPEC | 42000
1064 | ER_PARSE_ERROR | 42000
1065 | ER_EMPTY_QUERY | 42000
1066 | ER_NONUNIQ_TABLE | 42000
1067 | ER_INVALID_DEFAULT | 42000
1068 | ER_MULTIPLE_PRI_KEY | 42000
1069 | ER_TOO_MANY_KEYS | 42000
1070 | ER_TOO_MANY_KEY_PARTS | 42000
1071 | ER_TOO_LONG_KEY | 42000
1072 | ER_KEY_COLUMN_DOES_NOT_EXITS | 42000
1073 | ER_BLOB_USED_AS_KEY | 42000
1074 | ER_TOO_BIG_FIELDLENGTH | 42000
1075 | ER_WRONG_AUTO_KEY | 42000
1080 | ER_FORCING_CLOSE | 08S01
1081 | ER_IPSOCK_ERROR | 08S01
1082 | ER_NO_SUCH_INDEX | 42S12
1083 | ER_WRONG_FIELD_TERMINATORS | 42000
1084 | ER_BLOBS_AND_NO_TERMINATED | 42000
1090 | ER_CANT_REMOVE_ALL_FIELDS | 42000
1091 | ER_CANT_DROP_FIELD_OR_KEY | 42000
1101 | ER_BLOB_CANT_HAVE_DEFAULT | 42000
1102 | ER_WRONG_DB_NAME | 42000
1103 | ER_WRONG_TABLE_NAME | 42000
1104 | ER_TOO_BIG_SELECT | 42000
1106 | ER_UNKNOWN_PROCEDURE | 42000
1107 | ER_WRONG_PARAMCOUNT_TO_PROCEDURE | 42000
1109 | ER_UNKNOWN_TABLE | 42S02
1110 | ER_FIELD_SPECIFIED_TWICE | 42000
1112 | ER_UNSUPPORTED_EXTENSION | 42000
1113 | ER_TABLE_MUST_HAVE_COLUMNS | 42000
1115 | ER_UNKNOWN_CHARACTER_SET | 42000
1118 | ER_TOO_BIG_ROWSIZE | 42000
1120 | ER_WRONG_OUTER_JOIN | 42000
1121 | ER_NULL_COLUMN_IN_INDEX | 42000
1131 | ER_PASSWORD_ANONYMOUS_USER | 42000
1132 | ER_PASSWORD_NOT_ALLOWED | 42000
1133 | ER_PASSWORD_NO_MATCH | 42000
1136 | ER_WRONG_VALUE_COUNT_ON_ROW | 21S01
1138 | ER_INVALID_USE_OF_NULL | 22004
1139 | ER_REGEXP_ERROR | 42000
1140 | ER_MIX_OF_GROUP_FUNC_AND_FIELDS | 42000
1141 | ER_NONEXISTING_GRANT | 42000
1142 | ER_TABLEACCESS_DENIED_ERROR | 42000
1143 | ER_COLUMNACCESS_DENIED_ERROR | 42000
1144 | ER_ILLEGAL_GRANT_FOR_TABLE | 42000
1145 | ER_GRANT_WRONG_HOST_OR_USER | 42000
1146 | ER_NO_SUCH_TABLE | 42S02
1147 | ER_NONEXISTING_TABLE_GRANT | 42000
1148 | ER_NOT_ALLOWED_COMMAND | 42000
1149 | ER_SYNTAX_ERROR | 42000
1152 | ER_ABORTING_CONNECTION | 08S01
1153 | ER_NET_PACKET_TOO_LARGE | 08S01
1154 | ER_NET_READ_ERROR_FROM_PIPE | 08S01
1155 | ER_NET_FCNTL_ERROR | 08S01
1156 | ER_NET_PACKETS_OUT_OF_ORDER | 08S01
1157 | ER_NET_UNCOMPRESS_ERROR | 08S01
1158 | ER_NET_READ_ERROR | 08S01
1159 | ER_NET_READ_INTERRUPTED | 08S01
1160 | ER_NET_ERROR_ON_WRITE | 08S01
1161 | ER_NET_WRITE_INTERRUPTED | 08S01
1162 | ER_TOO_LONG_STRING | 42000
1163 | ER_TABLE_CANT_HANDLE_BLOB | 42000
1164 | ER_TABLE_CANT_HANDLE_AUTO_INCREMENT | 42000
1166 | ER_WRONG_COLUMN_NAME | 42000
1167 | ER_WRONG_KEY_COLUMN | 42000
1169 | ER_DUP_UNIQUE | 23000
1170 | ER_BLOB_KEY_WITHOUT_LENGTH | 42000
1171 | ER_PRIMARY_CANT_HAVE_NULL | 42000
1172 | ER_TOO_MANY_ROWS | 42000
1173 | ER_REQUIRES_PRIMARY_KEY | 42000
1176 | ER_KEY_DOES_NOT_EXITS | 42000
1177 | ER_CHECK_NO_SUCH_TABLE | 42000
1178 | ER_CHECK_NOT_IMPLEMENTED | 42000
1179 | ER_CANT_DO_THIS_DURING_AN_TRANSACTION | 25000
1184 | ER_NEW_ABORTING_CONNECTION | 08S01
1189 | ER_MASTER_NET_READ | 08S01
1190 | ER_MASTER_NET_WRITE | 08S01
1203 | ER_TOO_MANY_USER_CONNECTIONS | 42000
1205 | ER_LOCK_WAIT_TIMEOUT | 40001
1207 | ER_READ_ONLY_TRANSACTION | 25000
1211 | ER_NO_PERMISSION_TO_CREATE_USER | 42000
1213 | ER_LOCK_DEADLOCK | 40001
1216 | ER_NO_REFERENCED_ROW | 23000
1217 | ER_ROW_IS_REFERENCED | 23000
1218 | ER_CONNECT_TO_MASTER | 08S01
1222 | ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT | 21000
1226 | ER_USER_LIMIT_REACHED | 42000
1227 | ER_SPECIFIC_ACCESS_DENIED_ERROR | 42000
1230 | ER_NO_DEFAULT | 42000
1231 | ER_WRONG_VALUE_FOR_VAR | 42000
1232 | ER_WRONG_TYPE_FOR_VAR | 42000
1234 | ER_CANT_USE_OPTION_HERE | 42000
1235 | ER_NOT_SUPPORTED_YET | 42000
1239 | ER_WRONG_FK_DEF | 42000
1241 | ER_OPERAND_COLUMNS | 21000
1242 | ER_SUBQUERY_NO_1_ROW | 21000
1247 | ER_ILLEGAL_REFERENCE | 42S22
1248 | ER_DERIVED_MUST_HAVE_ALIAS | 42000
1249 | ER_SELECT_REDUCED | 01000
1250 | ER_TABLENAME_NOT_ALLOWED_HERE | 42000
1251 | ER_NOT_SUPPORTED_AUTH_MODE | 08004
1252 | ER_SPATIAL_CANT_HAVE_NULL | 42000
1253 | ER_COLLATION_CHARSET_MISMATCH | 42000
1261 | ER_WARN_TOO_FEW_RECORDS | 01000
1262 | ER_WARN_TOO_MANY_RECORDS | 01000
1263 | ER_WARN_NULL_TO_NOTNULL | 22004
1264 | ER_WARN_DATA_OUT_OF_RANGE | 22003
1265 | ER_WARN_DATA_TRUNCATED | 01000
1280 | ER_WRONG_NAME_FOR_INDEX | 42000
1281 | ER_WRONG_NAME_FOR_CATALOG | 42000
1286 | ER_UNKNOWN_STORAGE_ENGINE | 42000
1292 | ER_TRUNCATED_WRONG_VALUE | 22007
1303 | ER_SP_NO_RECURSIVE_CREATE | 2F003
1304 | ER_SP_ALREADY_EXISTS | 42000
1305 | ER_SP_DOES_NOT_EXIST | 42000
1308 | ER_SP_LILABEL_MISMATCH | 42000
1309 | ER_SP_LABEL_REDEFINE | 42000
1310 | ER_SP_LABEL_MISMATCH | 42000
1311 | ER_SP_UNINIT_VAR | 01000
1312 | ER_SP_BADSELECT | 0A000
1313 | ER_SP_BADRETURN | 42000
1314 | ER_SP_BADSTATEMENT | 0A000
1315 | ER_UPDATE_LOG_DEPRECATED_IGNORED | 42000
1316 | ER_UPDATE_LOG_DEPRECATED_TRANSLATED | 42000
1317 | ER_QUERY_INTERRUPTED | 70100
1318 | ER_SP_WRONG_NO_OF_ARGS | 42000
1319 | ER_SP_COND_MISMATCH | 42000
1320 | ER_SP_NORETURN | 42000
1321 | ER_SP_NORETURNEND | 2F005
1322 | ER_SP_BAD_CURSOR_QUERY | 42000
1323 | ER_SP_BAD_CURSOR_SELECT | 42000
1324 | ER_SP_CURSOR_MISMATCH | 42000
1325 | ER_SP_CURSOR_ALREADY_OPEN | 24000
1326 | ER_SP_CURSOR_NOT_OPEN | 24000
1327 | ER_SP_UNDECLARED_VAR | 42000
1329 | ER_SP_FETCH_NO_DATA | 02000
1330 | ER_SP_DUP_PARAM | 42000
1331 | ER_SP_DUP_VAR | 42000
1332 | ER_SP_DUP_COND | 42000
1333 | ER_SP_DUP_CURS | 42000
1335 | ER_SP_SUBSELECT_NYI | 0A000
1336 | ER_STMT_NOT_ALLOWED_IN_SF_OR_TRG | 0A000
1337 | ER_SP_VARCOND_AFTER_CURSHNDLR | 42000
1338 | ER_SP_CURSOR_AFTER_HANDLER | 42000
1339 | ER_SP_CASE_NOT_FOUND | 20000
1365 | ER_DIVISION_BY_ZERO | 22012
1367 | ER_ILLEGAL_VALUE_FOR_TYPE | 22007
1370 | ER_PROCACCESS_DENIED_ERROR | 42000
1397 | ER_XAER_NOTA | XAE04
1398 | ER_XAER_INVAL | XAE05
1399 | ER_XAER_RMFAIL | XAE07
1400 | ER_XAER_OUTSIDE | XAE09
1401 | ER_XA_RMERR | XAE03
1402 | ER_XA_RBROLLBACK | XA100
1403 | ER_NONEXISTING_PROC_GRANT | 42000
1406 | ER_DATA_TOO_LONG | 22001
1407 | ER_SP_BAD_SQLSTATE | 42000
1410 | ER_CANT_CREATE_USER_WITH_GRANT | 42000
1413 | ER_SP_DUP_HANDLER | 42000
1414 | ER_SP_NOT_VAR_ARG | 42000
1415 | ER_SP_NO_RETSET | 0A000
1416 | ER_CANT_CREATE_GEOMETRY_OBJECT | 22003
1425 | ER_TOO_BIG_SCALE | 42000
1426 | ER_TOO_BIG_PRECISION | 42000
1427 | ER_M_BIGGER_THAN_D | 42000
1437 | ER_TOO_LONG_BODY | 42000
1439 | ER_TOO_BIG_DISPLAYWIDTH | 42000
1440 | ER_XAER_DUPID | XAE08
1441 | ER_DATETIME_FUNCTION_OVERFLOW | 22008
1451 | ER_ROW_IS_REFERENCED_2 | 23000
1452 | ER_NO_REFERENCED_ROW_2 | 23000
1453 | ER_SP_BAD_VAR_SHADOW | 42000
1458 | ER_SP_WRONG_NAME | 42000
1460 | ER_SP_NO_AGGREGATE | 42000
1461 | ER_MAX_PREPARED_STMT_COUNT_REACHED | 42000
1463 | ER_NON_GROUPING_FIELD_USED | 42000
1557 | ER_FOREIGN_DUPLICATE_KEY | 23000
1568 | ER_CANT_CHANGE_TX_ISOLATION | 25001
1582 | ER_WRONG_PARAMCOUNT_TO_NATIVE_FCT | 42000
1583 | ER_WRONG_PARAMETERS_TO_NATIVE_FCT | 42000
1584 | ER_WRONG_PARAMETERS_TO_STORED_FCT | 42000
1586 | ER_DUP_ENTRY_WITH_KEY_NAME | 23000
1613 | ER_XA_RBTIMEOUT | XA106
1614 | ER_XA_RBDEADLOCK | XA102
1630 | ER_FUNC_INEXISTENT_NAME_COLLISION | 42000
1641 | ER_DUP_SIGNAL_SET | 42000
1642 | ER_SIGNAL_WARN | 01000
1643 | ER_SIGNAL_NOT_FOUND | 02000
1645 | ER_RESIGNAL_WITHOUT_ACTIVE_HANDLER | 0K000
1687 | ER_SPATIAL_MUST_HAVE_GEOM_COL | 42000
1690 | ER_DATA_OUT_OF_RANGE | 22003
1698 | ER_ACCESS_DENIED_NO_PASSWORD_ERROR | 28000
1701 | ER_TRUNCATE_ILLEGAL_FK | 42000
1758 | ER_DA_INVALID_CONDITION_NUMBER | 35000
1761 | ER_FOREIGN_DUPLICATE_KEY_WITH_CHILD_INFO | 23000
1762 | ER_FOREIGN_DUPLICATE_KEY_WITHOUT_CHILD_INFO | 23000
1792 | ER_CANT_EXECUTE_IN_READ_ONLY_TRANSACTION | 25006
1845 | ER_ALTER_OPERATION_NOT_SUPPORTED | 0A000
1846 | ER_ALTER_OPERATION_NOT_SUPPORTED_REASON | 0A000
1859 | ER_DUP_UNKNOWN_IN_INDEX | 23000
1873 | ER_ACCESS_DENIED_CHANGE_USER_ERROR | 28000
1887 | ER_GET_STACKED_DA_WITHOUT_ACTIVE_HANDLER | 0Z002
1903 | ER_INVALID_ARGUMENT_FOR_LOGARITHM | 2201E

Chapter 7 JDBC Concepts

Table of Contents

7.1 Connecting to MySQL Using the JDBC DriverManager Interface

7.2 Using JDBC Statement Objects to Execute SQL

7.3 Using JDBC CallableStatements to Execute Stored Procedures

7.4 Retrieving AUTO_INCREMENT Column Values through JDBC

This section provides some general JDBC background.

7.1 Connecting to MySQL Using the JDBC DriverManager Interface

When you are using JDBC outside of an application server, the DriverManager class manages the establishment of connections.

Specify to the DriverManager which JDBC drivers to try to make Connections with. The easiest way to do this is to use Class.forName() on the class that implements the java.sql.Driver interface. With MySQL Connector/J, the name of this class is com.mysql.cj.jdbc.Driver. With this method, you could use an external configuration file to supply the driver class name and driver parameters to use when connecting to a database.

The following section of Java code shows how you might register MySQL Connector/J from the main() method of your application. If testing this code, first read the installation section at Chapter 4, Connector/J Installation, to make sure you have connector installed correctly and the CLASSPATH set up. Also, ensure that MySQL is configured to accept external TCP/IP connections.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

// Notice, do not import com.mysql.cj.jdbc.*
// or you will have problems!

public class LoadDriver {
    public static void main(String[] args) {
        try {
            // The newInstance() call is a work around for some
            // broken Java implementations

            Class.forName("com.mysql.cj.jdbc.Driver").newInstance();
        } catch (Exception ex) {
            // handle the error
        }
    }
}

After the driver has been registered with the DriverManager, you can obtain a Connection instance that is connected to a particular database by calling DriverManager.getConnection():

Example 7.1 Connector/J: Obtaining a connection from the DriverManager

If you have not already done so, please review the portion of Section 7.1, “Connecting to MySQL Using the JDBC DriverManager Interface” above before working with the example below.

This example shows how you can obtain a Connection instance from the DriverManager. There are a few different signatures for the getConnection() method. Consult the API documentation that comes with your JDK for more specific information on how to use them.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

Connection conn = null;
...
try {
    conn =
       DriverManager.getConnection("jdbc:mysql://localhost/test?" +
                                   "user=minty&password=greatsqldb");

    // Do something with the Connection

   ...
} catch (SQLException ex) {
    // handle any errors
    System.out.println("SQLException: " + ex.getMessage());
    System.out.println("SQLState: " + ex.getSQLState());
    System.out.println("VendorError: " + ex.getErrorCode());
}

Once a Connection is established, it can be used to create Statement and PreparedStatement objects, as well as retrieve metadata about the database. This is explained in the following sections.

7.2 Using JDBC Statement Objects to Execute SQL

Statement objects allow you to execute basic SQL queries and retrieve the results through the ResultSet class, which is described later.

To create a Statement instance, you call the createStatement() method on the Connection object you have retrieved using one of the DriverManager.getConnection() or DataSource.getConnection() methods described earlier.

Once you have a Statement instance, you can execute a SELECT query by calling the executeQuery(String) method with the SQL you want to use.

To update data in the database, use the executeUpdate(String SQL) method. This method returns the number of rows matched by the update statement, not the number of rows that were modified.

If you do not know ahead of time whether the SQL statement will be a SELECT or an UPDATE/INSERT, then you can use the execute(String SQL) method. This method will return true if the SQL query was a SELECT, or false if it was an UPDATE, INSERT, or DELETE statement. If the statement was a SELECT query, you can retrieve the results by calling the getResultSet() method. If the statement was an UPDATE, INSERT, or DELETE statement, you can retrieve the affected rows count by calling getUpdateCount() on the Statement instance.

Example 7.2 Connector/J: Using java.sql.Statement to execute a SELECT query

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSet;

// assume that conn is an already created JDBC connection (see previous examples)

Statement stmt = null;
ResultSet rs = null;

try {
    stmt = conn.createStatement();
    rs = stmt.executeQuery("SELECT foo FROM bar");

    // or alternatively, if you don't know ahead of time that
    // the query will be a SELECT...

    if (stmt.execute("SELECT foo FROM bar")) {
        rs = stmt.getResultSet();
    }

    // Now do something with the ResultSet ....
}
catch (SQLException ex){
    // handle any errors
    System.out.println("SQLException: " + ex.getMessage());
    System.out.println("SQLState: " + ex.getSQLState());
    System.out.println("VendorError: " + ex.getErrorCode());
}
finally {
    // it is a good idea to release
    // resources in a finally{} block
    // in reverse-order of their creation
    // if they are no-longer needed

    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException sqlEx) { } // ignore

        rs = null;
    }

    if (stmt != null) {
        try {
            stmt.close();
        } catch (SQLException sqlEx) { } // ignore

        stmt = null;
    }
}

7.3 Using JDBC CallableStatements to Execute Stored Procedures

Connector/J fully implements the java.sql.CallableStatement interface, with the exception of the getParameterMetaData() method.

For more information on MySQL stored procedures, please refer to Using Stored Routines (Procedures and Functions).

Connector/J exposes stored procedure functionality through JDBC's CallableStatement interface.

Note

Current versions of MySQL server do not return enough information for the JDBC driver to provide result set metadata for callable statements. This means that when using CallableStatement, ResultSetMetaData may return NULL.

The following example shows a stored procedure that returns the value of inOutParam incremented by 1, and the string passed in using inputParam as a ResultSet:

Example 7.3 Connector/J: Calling Stored Procedures

CREATE PROCEDURE demoSp(IN inputParam VARCHAR(255), \
                        INOUT inOutParam INT)
BEGIN
    DECLARE z INT;
    SET z = inOutParam + 1;
    SET inOutParam = z;

    SELECT inputParam;

    SELECT CONCAT('zyxw', inputParam);
END

To use the demoSp procedure with Connector/J, follow these steps:

Prepare the callable statement by using Connection.prepareCall().

Notice that you have to use JDBC escape syntax, and that the parentheses surrounding the parameter placeholders are not optional:

Example 7.4 Connector/J: Using Connection.prepareCall()

import java.sql.CallableStatement;

...

    //
    // Prepare a call to the stored procedure 'demoSp'
    // with two parameters
    //
    // Notice the use of JDBC-escape syntax ({call ...})
    //

    CallableStatement cStmt = conn.prepareCall("{call demoSp(?, ?)}");

    cStmt.setString(1, "abcdefg");

Note

Connection.prepareCall() is an expensive method, due to the metadata retrieval that the driver performs to support output parameters. For performance reasons, minimize unnecessary calls to Connection.prepareCall() by reusing CallableStatement instances in your code.

Register the output parameters (if any exist)

To retrieve the values of output parameters (parameters specified as OUT or INOUT when you created the stored procedure), JDBC requires that they be specified before statement execution using the various registerOutputParameter() methods in the CallableStatement interface:

Example 7.5 Connector/J: Registering output parameters

import java.sql.Types;
...
//
// Connector/J supports both named and indexed
// output parameters. You can register output
// parameters using either method, as well
// as retrieve output parameters using either
// method, regardless of what method was
// used to register them.
//
// The following examples show how to use
// the various methods of registering
// output parameters (you should of course
// use only one registration per parameter).
//

//
// Registers the second parameter as output, and
// uses the type 'INTEGER' for values returned from
// getObject()
//

cStmt.registerOutParameter(2, Types.INTEGER);

//
// Registers the named parameter 'inOutParam', and
// uses the type 'INTEGER' for values returned from
// getObject()
//

cStmt.registerOutParameter("inOutParam", Types.INTEGER);
...

Set the input parameters (if any exist)

Input and in/out parameters are set as for PreparedStatement objects. However, CallableStatement also supports setting parameters by name:

Example 7.6 Connector/J: Setting CallableStatement input parameters

...

    //
    // Set a parameter by index
    //

    cStmt.setString(1, "abcdefg");

    //
    // Alternatively, set a parameter using
    // the parameter name
    //

    cStmt.setString("inputParameter", "abcdefg");

    //
    // Set the 'in/out' parameter using an index
    //

    cStmt.setInt(2, 1);

    //
    // Alternatively, set the 'in/out' parameter
    // by name
    //

    cStmt.setInt("inOutParam", 1);

...

Execute the CallableStatement, and retrieve any result sets or output parameters.

Although CallableStatement supports calling any of the Statement execute methods (executeUpdate(), executeQuery() or execute()), the most flexible method to call is execute(), as you do not need to know ahead of time if the stored procedure returns result sets:

Example 7.7 Connector/J: Retrieving results and output parameter values

...

    boolean hadResults = cStmt.execute();

    //
    // Process all returned result sets
    //

    while (hadResults) {
        ResultSet rs = cStmt.getResultSet();

        // process result set
        ...

        hadResults = cStmt.getMoreResults();
    }

    //
    // Retrieve output parameters
    //
    // Connector/J supports both index-based and
    // name-based retrieval
    //

    int outputValue = cStmt.getInt(2); // index-based

    outputValue = cStmt.getInt("inOutParam"); // name-based

...

7.4 Retrieving AUTO_INCREMENT Column Values through JDBC

getGeneratedKeys() is the preferred method to use if you need to retrieve AUTO_INCREMENT keys and through JDBC; this is illustrated in the first example below. The second example shows how you can retrieve the same value using a standard SELECT LAST_INSERT_ID() query. The final example shows how updatable result sets can retrieve the AUTO_INCREMENT value when using the insertRow() method.

Example 7.8 Connector/J: Retrieving AUTO_INCREMENT column values using Statement.getGeneratedKeys()

Statement stmt = null;
ResultSet rs = null;

try {

    //
    // Create a Statement instance that we can use for
    // 'normal' result sets assuming you have a
    // Connection 'conn' to a MySQL database already
    // available

    stmt = conn.createStatement();

    //
    // Issue the DDL queries for the table for this example
    //

    stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
    stmt.executeUpdate(
            "CREATE TABLE autoIncTutorial ("
            + "priKey INT NOT NULL AUTO_INCREMENT, "
            + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

    //
    // Insert one row that will generate an AUTO INCREMENT
    // key in the 'priKey' field
    //

    stmt.executeUpdate(
            "INSERT INTO autoIncTutorial (dataField) "
            + "values ('Can I Get the Auto Increment Field?')",
            Statement.RETURN_GENERATED_KEYS);

    //
    // Example of using Statement.getGeneratedKeys()
    // to retrieve the value of an auto-increment
    // value
    //

    int autoIncKeyFromApi = -1;

    rs = stmt.getGeneratedKeys();

    if (rs.next()) {
        autoIncKeyFromApi = rs.getInt(1);
    } else {

        // throw an exception from here
    }

    System.out.println("Key returned from getGeneratedKeys():"
        + autoIncKeyFromApi);
} finally {

    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException ex) {
            // ignore
        }
    }

    if (stmt != null) {
        try {
            stmt.close();
        } catch (SQLException ex) {
            // ignore
        }
    }
}

Example 7.9 Connector/J: Retrieving AUTO_INCREMENT column values using SELECT LAST_INSERT_ID()

Statement stmt = null;
ResultSet rs = null;

try {

    //
    // Create a Statement instance that we can use for
    // 'normal' result sets.

    stmt = conn.createStatement();

    //
    // Issue the DDL queries for the table for this example
    //

    stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
    stmt.executeUpdate(
            "CREATE TABLE autoIncTutorial ("
            + "priKey INT NOT NULL AUTO_INCREMENT, "
            + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

    //
    // Insert one row that will generate an AUTO INCREMENT
    // key in the 'priKey' field
    //

    stmt.executeUpdate(
            "INSERT INTO autoIncTutorial (dataField) "
            + "values ('Can I Get the Auto Increment Field?')");

    //
    // Use the MySQL LAST_INSERT_ID()
    // function to do the same thing as getGeneratedKeys()
    //

    int autoIncKeyFromFunc = -1;
    rs = stmt.executeQuery("SELECT LAST_INSERT_ID()");

    if (rs.next()) {
        autoIncKeyFromFunc = rs.getInt(1);
    } else {
        // throw an exception from here
    }

    System.out.println("Key returned from " +
                       "'SELECT LAST_INSERT_ID()': " +
                       autoIncKeyFromFunc);

} finally {

    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException ex) {
            // ignore
        }
    }

    if (stmt != null) {
        try {
            stmt.close();
        } catch (SQLException ex) {
            // ignore
        }
    }
}

Example 7.10 Connector/J: Retrieving AUTO_INCREMENT column values in Updatable ResultSets

Statement stmt = null;
ResultSet rs = null;

try {

    //
    // Create a Statement instance that we can use for
    // 'normal' result sets as well as an 'updatable'
    // one, assuming you have a Connection 'conn' to
    // a MySQL database already available
    //

    stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                                java.sql.ResultSet.CONCUR_UPDATABLE);

    //
    // Issue the DDL queries for the table for this example
    //

    stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
    stmt.executeUpdate(
            "CREATE TABLE autoIncTutorial ("
            + "priKey INT NOT NULL AUTO_INCREMENT, "
            + "dataField VARCHAR(64), PRIMARY KEY (priKey))");

    //
    // Example of retrieving an AUTO INCREMENT key
    // from an updatable result set
    //

    rs = stmt.executeQuery("SELECT priKey, dataField "
       + "FROM autoIncTutorial");

    rs.moveToInsertRow();

    rs.updateString("dataField", "AUTO INCREMENT here?");
    rs.insertRow();

    //
    // the driver adds rows at the end
    //

    rs.last();

    //
    // We should now be on the row we just inserted
    //

    int autoIncKeyFromRS = rs.getInt("priKey");

    System.out.println("Key returned for inserted row: "
        + autoIncKeyFromRS);

} finally {

    if (rs != null) {
        try {
            rs.close();
        } catch (SQLException ex) {
            // ignore
        }
    }

    if (stmt != null) {
        try {
            stmt.close();
        } catch (SQLException ex) {
            // ignore
        }
    }
}

Running the preceding example code should produce the following output:

Key returned from getGeneratedKeys(): 1
Key returned from SELECT LAST_INSERT_ID(): 1
Key returned for inserted row: 1

At times, it can be tricky to use the SELECT LAST_INSERT_ID() query, as that function's value is scoped to a connection. So, if some other query happens on the same connection, the value is overwritten. On the other hand, the getGeneratedKeys() method is scoped by the Statement instance, so it can be used even if other queries happen on the same connection, but not on the same Statement instance.

Chapter 8 Connection Pooling with Connector/J

Connection pooling is a technique of creating and managing a pool of connections that are ready for use by any thread that needs them. Connection pooling can greatly increase the performance of your Java application, while reducing overall resource usage.

How Connection Pooling Works

Most applications only need a thread to have access to a JDBC connection when they are actively processing a transaction, which often takes only milliseconds to complete. When not processing a transaction, the connection sits idle. Connection pooling enables the idle connection to be used by some other thread to do useful work.

In practice, when a thread needs to do work against a MySQL or other database with JDBC, it requests a connection from the pool. When the thread is finished using the connection, it returns it to the pool, so that it can be used by any other threads.

When the connection is loaned out from the pool, it is used exclusively by the thread that requested it. From a programming point of view, it is the same as if your thread called DriverManager.getConnection() every time it needed a JDBC connection. With connection pooling, your thread may end up using either a new connection or an already-existing connection.

Benefits of Connection Pooling

The main benefits to connection pooling are:

Reduced connection creation time.

Although this is not usually an issue with the quick connection setup that MySQL offers compared to other databases, creating new JDBC connections still incurs networking and JDBC driver overhead that will be avoided if connections are recycled.

Simplified programming model.

When using connection pooling, each individual thread can act as though it has created its own JDBC connection, allowing you to use straightforward JDBC programming techniques.

Controlled resource usage.

If you create a new connection every time a thread needs one rather than using connection pooling, your application's resource usage can be wasteful, and it could lead to unpredictable behaviors for your application when it is under a heavy load.

Using Connection Pooling with Connector/J

The concept of connection pooling in JDBC has been standardized through the JDBC 2.0 Optional interfaces, and all major application servers have implementations of these APIs that work with MySQL Connector/J.

Generally, you configure a connection pool in your application server configuration files, and access it through the Java Naming and Directory Interface (JNDI). The following code shows how you might use a connection pool from an application deployed in a J2EE application server:

Example 8.1 Connector/J: Using a connection pool with a J2EE application server

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;

import javax.naming.InitialContext;
import javax.sql.DataSource;

public class MyServletJspOrEjb {

    public void doSomething() throws Exception {
        /*
         * Create a JNDI Initial context to be able to
         *  lookup  the DataSource
         *
         * In production-level code, this should be cached as
         * an instance or static variable, as it can
         * be quite expensive to create a JNDI context.
         *
         * Note: This code only works when you are using servlets
         * or EJBs in a J2EE application server. If you are
         * using connection pooling in standalone Java code, you
         * will have to create/configure datasources using whatever
         * mechanisms your particular connection pooling library
         * provides.
         */

        InitialContext ctx = new InitialContext();

         /*
          * Lookup the DataSource, which will be backed by a pool
          * that the application server provides. DataSource instances
          * are also a good candidate for caching as an instance
          * variable, as JNDI lookups can be expensive as well.
          */

        DataSource ds =
          (DataSource)ctx.lookup("java:comp/env/jdbc/MySQLDB");

        /*
         * The following code is what would actually be in your
         * Servlet, JSP or EJB 'service' method...where you need
         * to work with a JDBC connection.
         */

        Connection conn = null;
        Statement stmt = null;

        try {
            conn = ds.getConnection();

            /*
             * Now, use normal JDBC programming to work with
             * MySQL, making sure to close each resource when you're
             * finished with it, which permits the connection pool
             * resources to be recovered as quickly as possible
             */

            stmt = conn.createStatement();
            stmt.execute("SOME SQL QUERY");

            stmt.close();
            stmt = null;

            conn.close();
            conn = null;
        } finally {
            /*
             * close any jdbc instances here that weren't
             * explicitly closed during normal code path, so
             * that we don't 'leak' resources...
             */

            if (stmt != null) {
                try {
                    stmt.close();
                } catch (sqlexception sqlex) {
                    // ignore, as we can't do anything about it here
                }

                stmt = null;
            }

            if (conn != null) {
                try {
                    conn.close();
                } catch (sqlexception sqlex) {
                    // ignore, as we can't do anything about it here
                }

                conn = null;
            }
        }
    }
}

As shown in the example above, after obtaining the JNDI InitialContext, and looking up the DataSource, the rest of the code follows familiar JDBC conventions.

When using connection pooling, always make sure that connections, and anything created by them (such as statements or result sets) are closed. This rule applies no matter what happens in your code (exceptions, flow-of-control, and so forth). When these objects are closed, they can be re-used; otherwise, they will be stranded, which means that the MySQL server resources they represent (such as buffers, locks, or sockets) are tied up for some time, or in the worst case can be tied up forever.

Sizing the Connection Pool

Each connection to MySQL has overhead (memory, CPU, context switches, and so forth) on both the client and server side. Every connection limits how many resources there are available to your application as well as the MySQL server. Many of these resources will be used whether or not the connection is actually doing any useful work! Connection pools can be tuned to maximize performance, while keeping resource utilization below the point where your application will start to fail rather than just run slower.

The optimal size for the connection pool depends on anticipated load and average database transaction time. In practice, the optimal connection pool size can be smaller than you might expect. If you take Oracle's Java Petstore blueprint application for example, a connection pool of 15-20 connections can serve a relatively moderate load (600 concurrent users) using MySQL and Tomcat with acceptable response times.

To correctly size a connection pool for your application, create load test scripts with tools such as Apache JMeter or The Grinder, and load test your application.

An easy way to determine a starting point is to configure your connection pool's maximum number of connections to be unbounded, run a load test, and measure the largest amount of concurrently used connections. You can then work backward from there to determine what values of minimum and maximum pooled connections give the best performance for your particular application.

Validating Connections

MySQL Connector/J can validate the connection by executing a lightweight ping against a server. In the case of load-balanced connections, this is performed against all active pooled internal connections that are retained. This is beneficial to Java applications using connection pools, as the pool can use this feature to validate connections. Depending on your connection pool and configuration, this validation can be carried out at different times:

Before the pool returns a connection to the application.

When the application returns a connection to the pool.

During periodic checks of idle connections.

To use this feature, specify a validation query in your connection pool that starts with /* ping */. Note that the syntax must be exactly as specified. This will cause the driver send a ping to the server and return a dummy lightweight result set. When using a ReplicationConnection or LoadBalancedConnection, the ping will be sent across all active connections.

It is critical that the syntax be specified correctly. The syntax needs to be exact for reasons of efficiency, as this test is done for every statement that is executed:

protected static final String PING_MARKER = "/* ping */";
...
if (sql.charAt(0) == '/') {
if (sql.startsWith(PING_MARKER)) {
doPingInstead();
...

None of the following snippets will work, because the ping syntax is sensitive to whitespace, capitalization, and placement:

sql = "/* PING */ SELECT 1";
sql = "SELECT 1 /* ping*/";
sql = "/*ping*/ SELECT 1";
sql = " /* ping */ SELECT 1";
sql = "/*to ping or not to ping*/ SELECT 1";

All of the previous statements will issue a normal SELECT statement and will not be transformed into the lightweight ping. Further, for load-balanced connections, the statement will be executed against one connection in the internal pool, rather than validating each underlying physical connection. This results in the non-active physical connections assuming a stale state, and they may die. If Connector/J then re-balances, it might select a dead connection, resulting in an exception being passed to the application. To help prevent this, you can use loadBalanceValidateConnectionOnSwapServer to validate the connection before use.

If your Connector/J deployment uses a connection pool that allows you to specify a validation query, take advantage of it, but ensure that the query starts exactly with /* ping */. This is particularly important if you are using the load-balancing or replication-aware features of Connector/J, as it will help keep alive connections which otherwise will go stale and die, causing problems later.

Chapter 9 Multi-Host Connections

Table of Contents

9.1 Configuring Server Failover

9.2 Configuring Load Balancing with Connector/J

9.3 Configuring Master/Slave Replication with Connector/J

9.4 Advanced Load-balancing and Failover Configuration

The following sections discuss a number of topics that involve multi-host connections, namely, server load-balancing, failover, and replication.

Developers should know the following things about multi-host connections that are managed through Connector/J:

Each multi-host connection is a wrapper of the underlying physical connections.

Each of the underlying physical connections has its own session. Sessions cannot be tracked, shared, or copied, given the MySQL architecture.

Every switch between physical connections means a switch between sessions.

Within a transaction boundary, there are no switches between physical connections. Beyond a transaction boundary, there is no guarantee that a switch does not occur.

Note

If an application reuses session-scope data (for example, variables, SSPs) beyond a transaction boundary, failures are possible, as a switch between the physical connections (which is also a switch between sessions) might occur. Therefore, the application should re-prepare the session data and also restart the last transaction in case of an exception, or it should re-prepare session data for each new transaction if it does not want to deal with exception handling.

9.1 Configuring Server Failover

MySQL Connector/J supports server failover. A failover happens when connection-related errors occur for an underlying, active connection. The connection errors are, by default, propagated to the client, which has to handle them by, for example, recreating the working objects (Statement, ResultSet, etc.) and restarting the processes. Sometimes, the driver might eventually fall back to the original host automatically before the client application continues to run, in which case the host switch is transparent and the client application will not even notice it.

A connection using failover support works just like a standard connection: the client does not experience any disruptions in the failover process. This means the client can rely on the same connection instance even if two successive statements might be executed on two different physical hosts. However, this does not mean the client does not have to deal with the exception that triggered the server switch.

The failover is configured at the initial setup stage of the server connection by the connection URL (see explanations for its format here):

jdbc:mysql://[primary host][:port],[secondary host 1][:port][,[secondary host 2][:port]]...[/[database]]»
[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

The host list in the connection URL comprises of two types of hosts, the primary and the secondary. When starting a new connection, the driver always tries to connect to the primary host first and, if required, fails over to the secondary hosts on the list sequentially when communication problems are experienced. Even if the initial connection to the primary host fails and the driver gets connected to a secondary host, the primary host never loses its special status: for example, it can be configured with an access mode distinct from those of the secondary hosts, and it can be put on a higher priority when a host is to be picked during a failover process.

The failover support is configured by the following connection properties (their functions are explained in the paragraphs below):

failOverReadOnly

secondsBeforeRetryMaster

queriesBeforeRetryMaster

retriesAllDown

autoReconnect

autoReconnectForPools

Configuring Connection Access Mode

As with any standard connection, the initial connection to the primary host is in read/write mode. However, if the driver fails to establish the initial connection to the primary host and it automatically switches to the next host on the list, the access mode now depends on the value of the property failOverReadOnly, which is “true” by default. The same happens if the driver is initially connected to the primary host and, because of some connection failure, it fails over to a secondary host. Every time the connection falls back to the primary host, its access mode will be read/write, irrespective of whether or not the primary host has been connected to before. The connection access mode can be changed any time at runtime by calling the method Connection.setReadOnly(boolean), which partially overrides the property failOverReadOnly. When failOverReadOnly=false and the access mode is explicitly set to either true or false, it becomes the mode for every connection after a host switch, no matter what host type are being connected to; but, if failOverReadOnly=true, changing the access mode to read/write is only possible if the driver is connecting to the primary host; however, even if the access mode cannot be changed for the current connection, the driver remembers the client's last intention and, when falling back to the primary host, that is the mode that will be used. For an illustration, see the following successions of events with a two-host connection.

Sequence A, with failOverReadOnly=true:

Connects to primary host in read/write mode

Sets Connection.setReadOnly(true); primary host now in read-only mode

Failover event; connects to secondary host in read-only mode

Sets Connection.setReadOnly(false); secondary host remains in read-only mode

Falls back to primary host; connection now in read/write mode

Sequence B, with failOverReadOnly=false

Connects to primary host in read/write mode

Sets Connection.setReadOnly(true); primary host now in read-only mode

Failover event; connects to secondary host in read-only mode

Set Connection.setReadOnly(false); connection to secondary host switches to read/write mode

Falls back to primary host; connection now in read/write mode

The difference between the two scenarios is in step 4: the access mode for the secondary host in sequence A does not change at that step, but the driver remembers and uses the set mode when falling back to the primary host, which would be read-only otherwise; but in sequence B, the access mode for the secondary host changes immediately.

Configuring Fallback to Primary Host

As already mentioned, the primary host is special in the failover arrangement when it comes to the host's access mode. Additionally, the driver tries to fall back to the primary host as soon as possible by default, even if no communication exception occurs. Two properties, secondsBeforeRetryMaster and queriesBeforeRetryMaster, determine when the driver is ready to retry a reconnection to the primary host (the Master in the property names stands for the primary host of our connection URL, which is not necessarily a master host in a replication setup):

secondsBeforeRetryMaster determines how much time the driver waits before trying to fall back to the primary host

queriesBeforeRetryMaster determines the number of queries that are executed before the driver tries to fall back to the primary host. Note that for the driver, each call to a Statement.execute*() method increments the query execution counter; therefore, when calls are made to Statement.executeBatch() or if allowMultiQueries or rewriteBatchStatements are enabled, the driver may not have an accurate count of the actual number of queries executed on the server. Also, the driver calls the Statement.execute*() methods internally in several occasions. All these mean you can only use queriesBeforeRetryMaster only as a coarse specification for when to fall back to the primary host.

In general, an attempt to fallback to the primary host is made when at least one of the conditions specified by the two properties is met, and the attempt always takes place at transaction boundaries. However, if auto-commit is turned off, the check happens only when the method Connection.commit() or Connection.rollback() is called. The automatic fallback to the primary host can be turned off by setting simultaneously secondsBeforeRetryMaster and queriesBeforeRetryMaster to “0”. Setting only one of the properties to “0” only disables one part of the check.

Configuring Reconnection Attempts

When establishing a new connection or when a failover event occurs, the driver tries to connect successively to the next candidate on the host list. When the end of the list has been reached, it restarts all over again from the beginning of the list; however, the primary host is skipped over, if (a) NOT all the secondary hosts have already been tested at least once, AND (b) the fallback conditions defined by secondsBeforeRetryMaster and queriesBeforeRetryMaster are not yet fulfilled. Each run-through of the whole host list, (which is not necessarily completed at the end of the host list) counts as a single connection attempt. The driver tries as many connection attempts as specified by the value of the property retriesAllDown.

Seamless Reconnection

Although not recommended, you can make the driver perform failovers without invalidating the active Statement or ResultSet instances by setting either the parameter autoReconnect or autoReconnectForPools to true. This allows the client to continue using the same object instances after a failover event, without taking any exceptional measures. This, however, may lead to unexpected results: for example, if the driver is connected to the primary host with read/write access mode and it fails-over to a secondary host in real-only mode, further attempts to issue data-changing queries will result in errors, and the client will not be aware of that. This limitation is particularly relevant when using data streaming: after the failover, the ResultSet looks to be alright, but the underlying connection may have changed already, and no backing cursor is available anymore.

9.2 Configuring Load Balancing with Connector/J

Connector/J has long provided an effective means to distribute read/write load across multiple MySQL server instances for Cluster or master-master replication deployments. You can dynamically configure load-balanced connections, with no service outage. In-process transactions are not lost, and no application exceptions are generated if any application is trying to use that particular server instance.

The load balancing is configured at the initial setup stage of the server connection by the following connection URL, which has a similar format as the general JDBC URL for MySQL connection, but a specialized scheme:

jdbc:mysql:loadbalance://[host1][:port],[host2][:port][,[host3][:port]]...[/[database]] »
[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

There are two configuration properties associated with this functionality:

loadBalanceConnectionGroup – This provides the ability to group connections from different sources. This allows you to manage these JDBC sources within a single class loader in any combination you choose. If they use the same configuration, and you want to manage them as a logical single group, give them the same name. This is the key property for management: if you do not define a name (string) for loadBalanceConnectionGroup, you cannot manage the connections. All load-balanced connections sharing the same loadBalanceConnectionGroup value, regardless of how the application creates them, will be managed together.

ha.enableJMX – The ability to manage the connections is exposed when you define a loadBalanceConnectionGroup; but if you want to manage this externally, enable JMX by setting this property to true. This enables a JMX implementation, which exposes the management and monitoring operations of a connection group. Further, start your application with the -Dcom.sun.management.jmxremote JVM flag. You can then perform connect and perform operations using a JMX client such as jconsole.

Once a connection has been made using the correct connection properties, a number of monitoring properties are available:

Current active host count.

Current active physical connection count.

Current active logical connection count.

Total logical connections created.

Total transaction count.

The following management operations can also be performed:

Add host.

Remove host.

The JMX interface, com.mysql.cj.jdbc.jmx.LoadBalanceConnectionGroupManagerMBean, has the following methods:

int getActiveHostCount(String group);

int getTotalHostCount(String group);

long getTotalLogicalConnectionCount(String group);

long getActiveLogicalConnectionCount(String group);

long getActivePhysicalConnectionCount(String group);

long getTotalPhysicalConnectionCount(String group);

long getTotalTransactionCount(String group);

void removeHost(String group, String host) throws SQLException;

void stopNewConnectionsToHost(String group, String host) throws SQLException;

void addHost(String group, String host, boolean forExisting);

String getActiveHostsList(String group);

String getRegisteredConnectionGroups();

The getRegisteredConnectionGroups() method returns the names of all connection groups defined in that class loader.

You can test this setup with the following code:

public class Test {

    private static String URL = "jdbc:mysql:loadbalance://" +
        "localhost:3306,localhost:3310/test?" +
        "loadBalanceConnectionGroup=first&ha.enableJMX=true";

    public static void main(String[] args) throws Exception {
        new Thread(new Repeater()).start();
        new Thread(new Repeater()).start();
        new Thread(new Repeater()).start();
    }

    static Connection getNewConnection() throws SQLException, ClassNotFoundException {
        Class.forName("com.mysql.cj.jdbc.Driver");
        return DriverManager.getConnection(URL, "root", "");
    }

    static void executeSimpleTransaction(Connection c, int conn, int trans){
        try {
            c.setAutoCommit(false);
            Statement s = c.createStatement();
            s.executeQuery("SELECT SLEEP(1) /* Connection: " + conn + ", transaction: " + trans + " */");
            c.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static class Repeater implements Runnable {
        public void run() {
            for(int i=0; i < 100; i++){
                try {
                    Connection c = getNewConnection();
                    for(int j=0; j < 10; j++){
                        executeSimpleTransaction(c, i, j);
                        Thread.sleep(Math.round(100 * Math.random()));
                    }
                    c.close();
                    Thread.sleep(100);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

After compiling, the application can be started with the -Dcom.sun.management.jmxremote flag, to enable remote management. jconsole can then be started. The Test main class will be listed by jconsole. Select this and click Connect. You can then navigate to the com.mysql.cj.jdbc.jmx.LoadBalanceConnectionGroupManager bean. At this point, you can click on various operations and examine the returned result.

If you now had an additional instance of MySQL running on port 3309, you could ensure that Connector/J starts using it by using the addHost(), which is exposed in jconsole. Note that these operations can be performed dynamically without having to stop the application running.

For further information on the combination of load balancing and failover, see Section 9.4, “Advanced Load-balancing and Failover Configuration”.

9.3 Configuring Master/Slave Replication with Connector/J

This section describe a number of features of Connector/J's support for replication-aware deployments.

The replication is configured at the initial setup stage of the server connection by the connection URL, which has a similar format as the general JDBC URL for MySQL connection, but a specialized scheme:

jdbc:mysql:replication://[master host][:port],[slave host 1][:port][,[slave host 2][:port]]...[/[database]] »
[?propertyName1=propertyValue1[&propertyName2=propertyValue2]...]

Users may specify the property allowMasterDownConnections=true to allow Connection objects to be created even though no master hosts are reachable. Such Connection objects report they are read-only, and isMasterConnection() returns false for them. The Connection tests for available master hosts when Connection.setReadOnly(false) is called, throwing an SQLException if it cannot establish a connection to a master, or switching to a master connection if the host is available.

Users may specify the property allowSlavesDownConnections=true to allow Connection objects to be created even though no slave hosts are reachable. A Connection then, at runtime, tests for available slave hosts when Connection.setReadOnly(true) is called (see explanation for the method below), throwing an SQLException if it cannot establish a connection to a slave, unless the property readFromMasterWhenNoSlaves is set to be “true” (see below for a description of the property).

Scaling out Read Load by Distributing Read Traffic to Slaves

Connector/J supports replication-aware connections. It can automatically send queries to a read/write master, or a failover or round-robin loadbalanced set of slaves based on the state of Connection.getReadOnly().

An application signals that it wants a transaction to be read-only by calling Connection.setReadOnly(true). The replication-aware connection will use one of the slave connections, which are load-balanced per slave host using a round-robin scheme. A given connection is sticky to a slave until a transaction boundary command (a commit or rollback) is issued, or until the slave is removed from service. After calling Connection.setReadOnly(true), if you want to allow connection to a master when no slaves are available, set the property readFromMasterWhenNoSlaves to “true.” Notice that the master host will be used in read-only state in those cases, as if it is a slave host. Also notice that setting readFromMasterWhenNoSlaves=true might result in an extra load for the master host in a transparent manner.

If you have a write transaction, or if you have a read that is time-sensitive (remember, replication in MySQL is asynchronous), set the connection to be not read-only, by calling Connection.setReadOnly(false) and the driver will ensure that further calls are sent to the master MySQL server. The driver takes care of propagating the current state of autocommit, isolation level, and catalog between all of the connections that it uses to accomplish this load balancing functionality.

To enable this functionality, use the specialized replication scheme ( jdbc:mysql:replication://) when connecting to the server.

Here is a short example of how a replication-aware connection might be used in a standalone application:

import java.sql.Connection;
import java.sql.ResultSet;
import java.util.Properties;
import java.sql.DriverManager;

public class ReplicationDemo {

  public static void main(String[] args) throws Exception {

    Properties props = new Properties();

    // We want this for failover on the slaves
    props.put("autoReconnect", "true");

    // We want to load balance between the slaves
    props.put("roundRobinLoadBalance", "true");

    props.put("user", "foo");
    props.put("password", "bar");

    //
    // Looks like a normal MySQL JDBC url, with a
    // comma-separated list of hosts, the first
    // being the 'master', the rest being any number
    // of slaves that the driver will load balance against
    //

    Connection conn =
        DriverManager.getConnection("jdbc:mysql:replication://master,slave1,slave2,slave3/test",
            props);

    //
    // Perform read/write work on the master
    // by setting the read-only flag to "false"
    //

    conn.setReadOnly(false);
    conn.setAutoCommit(false);
    conn.createStatement().executeUpdate("UPDATE some_table ....");
    conn.commit();

    //
    // Now, do a query from a slave, the driver automatically picks one
    // from the list
    //

    conn.setReadOnly(true);

    ResultSet rs =
      conn.createStatement().executeQuery("SELECT a,b FROM alt_table");

     .......
  }
}

Consider using the Load Balancing JDBC Pool (lbpool) tool, which provides a wrapper around the standard JDBC driver and enables you to use DB connection pools that includes checks for system failures and uneven load distribution. For more information, see Load Balancing JDBC Driver for MySQL (mysql-lbpool).

Support for Multiple-Master Replication Topographies

Connector/J supports multi-master replication topographies.

The connection URL for replication discussed earlier (i.e., in the format of jdbc:mysql:replication://master,slave1,slave2,slave3/test) assumes that the first (and only the first) host is the master. Supporting deployments with an arbitrary number of masters and slaves requires a different URL syntax for specifying the hosts and the properties for specific hosts, which is just an expansion of the URL syntax discussed in Alternate Format for JDBC URLs with the property type=[master|slave]; for example:

jdbc:mysql://address=(type=master)(host=master1host),address=(type=master)(host=master2host),address=(type=slave)(host=slave1host)/database

Connector/J uses a load-balanced connection internally for management of the master connections, which means that ReplicationConnection, when configured to use multiple masters, exposes the same options to balance load across master hosts as described in Section 9.2, “Configuring Load Balancing with Connector/J”.

Live Reconfiguration of Replication Topography

Connector/J also supports live management of replication host (single or multi-master) topographies. This enables users to promote slaves for Java applications without requiring an application restart.

The replication hosts are most effectively managed in the context of a replication connection group. A ReplicationConnectionGroup class represents a logical grouping of connections which can be managed together. There may be one or more such replication connection groups in a given Java class loader (there can be an application with two different JDBC resources needing to be managed independently). This key class exposes host management methods for replication connections, and ReplicationConnection objects register themselves with the appropriate ReplicationConnectionGroup if a value for the new replicationConnectionGroup property is specified. The ReplicationConnectionGroup object tracks these connections until they are closed, and it is used to manipulate the hosts associated with these connections.

Some important methods related to host management include:

getMasterHosts(): Returns a collection of strings representing the hosts configured as masters

getSlaveHosts(): Returns a collection of strings representing the hosts configured as slaves

addSlaveHost(String host): Adds new host to pool of possible slave hosts for selection at start of new read-only workload

promoteSlaveToMaster(String host): Removes the host from the pool of potential slaves for future read-only processes (existing read-only process is allowed to continue to completion) and adds the host to the pool of potential master hosts

removeSlaveHost(String host, boolean closeGently): Removes the host (host name match must be exact) from the list of configured slaves; if closeGently is false, existing connections which have this host as currently active will be closed hardly (application should expect exceptions)

removeMasterHost(String host, boolean closeGently): Same as removeSlaveHost(), but removes the host from the list of configured masters

Some useful management metrics include:

getConnectionCountWithHostAsSlave(String host): Returns the number of ReplicationConnection objects that have the given host configured as a possible slave

getConnectionCountWithHostAsMaster(String host): Returns the number of ReplicationConnection objects that have the given host configured as a possible master

getNumberOfSlavesAdded(): Returns the number of times a slave host has been dynamically added to the group pool

getNumberOfSlavesRemoved(): Returns the number of times a slave host has been dynamically removed from the group pool

getNumberOfSlavePromotions(): Returns the number of times a slave host has been promoted to a master

getTotalConnectionCount(): Returns the number of ReplicationConnection objects which have been registered with this group

getActiveConnectionCount(): Returns the number of ReplicationConnection objects currently being managed by this group

ReplicationConnectionGroupManager

com.mysql.cj.jdbc.ha.ReplicationConnectionGroupManager provides access to the replication connection groups, together with some utility methods.

getConnectionGroup(String groupName): Returns the ReplicationConnectionGroup object matching the groupName provided

The other methods in ReplicationConnectionGroupManager mirror those of ReplicationConnectionGroup, except that the first argument is a String group name. These methods will operate on all matching ReplicationConnectionGroups, which are helpful for removing a server from service and have it decommissioned across all possible ReplicationConnectionGroups.

These methods might be useful for in-JVM management of replication hosts if an application triggers topography changes. For managing host configurations from outside the JVM, JMX can be used.

Using JMX for Managing Replication Hosts

When Connector/J is started with ha.enableJMX=true and a value set for the property replicationConnectionGroup, a JMX MBean will be registered, allowing manipulation of replication hosts by a JMX client. The MBean interface is defined in com.mysql.cj.jdbc.jmx.ReplicationGroupManagerMBean, and leverages the ReplicationConnectionGroupManager static methods:

 public abstract void addSlaveHost(String groupFilter, String host) throws SQLException;
 public abstract void removeSlaveHost(String groupFilter, String host) throws SQLException;
 public abstract void promoteSlaveToMaster(String groupFilter, String host) throws SQLException;
 public abstract void removeMasterHost(String groupFilter, String host) throws SQLException;
 public abstract String getMasterHostsList(String group);
 public abstract String getSlaveHostsList(String group);
 public abstract String getRegisteredConnectionGroups();
 public abstract int getActiveMasterHostCount(String group);
 public abstract int getActiveSlaveHostCount(String group);
 public abstract int getSlavePromotionCount(String group);
 public abstract long getTotalLogicalConnectionCount(String group);
 public abstract long getActiveLogicalConnectionCount(String group);

9.4 Advanced Load-balancing and Failover Configuration

Connector/J provides a useful load-balancing implementation for MySQL Cluster or multi-master deployments, as explained in Section 9.2, “Configuring Load Balancing with Connector/J” and Support for Multiple-Master Replication Topographies. This same implementation is used for balancing load between read-only slaves for replication-aware connections.

When trying to balance workload between multiple servers, the driver has to determine when it is safe to swap servers, doing so in the middle of a transaction, for example, could cause problems. It is important not to lose state information. For this reason, Connector/J will only try to pick a new server when one of the following happens:

At transaction boundaries (transactions are explicitly committed or rolled back).

A communication exception (SQL State starting with "08") is encountered.

When a SQLException matches conditions defined by user, using the extension points defined by the loadBalanceSQLStateFailover, loadBalanceSQLExceptionSubclassFailover or loadBalanceExceptionChecker properties.

The third condition revolves around three properties, which allow you to control which SQLExceptions trigger failover:

loadBalanceExceptionChecker - The loadBalanceExceptionChecker property is really the key. This takes a fully-qualified class name which implements the new com.mysql.cj.jdbc.LoadBalanceExceptionChecker interface. This interface is very simple, and you only need to implement the following method:

public boolean shouldExceptionTriggerFailover(SQLException ex)

A SQLException is passed in, and a boolean returned. A value of true triggers a failover, false does not.

You can use this to implement your own custom logic. An example where this might be useful is when dealing with transient errors when using MySQL Cluster, where certain buffers may become overloaded. The following code snippet illustrates this:

public class NdbLoadBalanceExceptionChecker
 extends StandardLoadBalanceExceptionChecker {

 public boolean shouldExceptionTriggerFailover(SQLException ex) {
  return super.shouldExceptionTriggerFailover(ex)
    ||  checkNdbException(ex);
 }

 private boolean checkNdbException(SQLException ex){
 // Have to parse the message since most NDB errors
 // are mapped to the same DEMC.
  return (ex.getMessage().startsWith("Lock wait timeout exceeded") ||
  (ex.getMessage().startsWith("Got temporary error")
  && ex.getMessage().endsWith("from NDB")));
 }
}

The code above extends com.mysql.cj.jdbc.StandardLoadBalanceExceptionChecker, which is the default implementation. There are a few convenient shortcuts built into this, for those who want to have some level of control using properties, without writing Java code. This default implementation uses the two remaining properties: loadBalanceSQLStateFailover and loadBalanceSQLExceptionSubclassFailover.

loadBalanceSQLStateFailover - allows you to define a comma-delimited list of SQLState code prefixes, against which a SQLException is compared. If the prefix matches, failover is triggered. So, for example, the following would trigger a failover if a given SQLException starts with "00", or is "12345":

loadBalanceSQLStateFailover=00,12345

loadBalanceSQLExceptionSubclassFailover - can be used in conjunction with loadBalanceSQLStateFailover or on its own. If you want certain subclasses of SQLException to trigger failover, simply provide a comma-delimited list of fully-qualified class or interface names to check against. For example, if you want all SQLTransientConnectionExceptions to trigger failover, you would specify:

loadBalanceSQLExceptionSubclassFailover=java.sql.SQLTransientConnectionException

While the three failover conditions enumerated earlier suit most situations, if autocommit is enabled, Connector/J never re-balances, and continues using the same physical connection. This can be problematic, particularly when load-balancing is being used to distribute read-only load across multiple slaves. However, Connector/J can be configured to re-balance after a certain number of statements are executed, when autocommit is enabled. This functionality is dependent upon the following properties:

loadBalanceAutoCommitStatementThreshold – defines the number of matching statements which will trigger the driver to potentially swap physical server connections. The default value, 0, retains the behavior that connections with autocommit enabled are never balanced.

loadBalanceAutoCommitStatementRegex – the regular expression against which statements must match. The default value, blank, matches all statements. So, for example, using the following properties will cause Connector/J to re-balance after every third statement that contains the string “test”:

loadBalanceAutoCommitStatementThreshold=3
loadBalanceAutoCommitStatementRegex=.*test.*

loadBalanceAutoCommitStatementRegex can prove useful in a number of situations. Your application may use temporary tables, server-side session state variables, or connection state, where letting the driver arbitrarily swap physical connections before processing is complete could cause data loss or other problems. This allows you to identify a trigger statement that is only executed when it is safe to swap physical connections.

Chapter 10 Using the Connector/J Interceptor Classes

An interceptor is a software design pattern that provides a transparent way to extend or modify some aspect of a program, similar to a user exit. No recompiling is required. With Connector/J, the interceptors are enabled and disabled by updating the connection string to refer to different sets of interceptor classes that you instantiate.

The connection properties that control the interceptors are explained in Section 6.1, “Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J”:

connectionLifecycleInterceptors, where you specify the fully qualified names of classes that implement the com.mysql.cj.api.jdbc.interceptors.ConnectionLifecycleInterceptor interface. In these kinds of interceptor classes, you might log events such as rollbacks, measure the time between transaction start and end, or count events such as calls to setAutoCommit().

exceptionInterceptors, where you specify the fully qualified names of classes that implement the com.mysql.cj.api.exceptions.ExceptionInterceptor interface. In these kinds of interceptor classes, you might add extra diagnostic information to exceptions that can have multiple causes or indicate a problem with server settings. exceptionInterceptors classes are called when handling an Exception thrown from Connector/J code.

statementInterceptors, where you specify the fully qualified names of classes that implement the com.mysql.cj.api.jdbc.interceptors.StatementInterceptorV2 interface. In these kinds of interceptor classes, you might change or augment the processing done by certain kinds of statements, such as automatically checking for queried data in a memcached server, rewriting slow queries, logging information about statement execution, or route requests to remote servers.

Chapter 11 Using Connector/J with Tomcat

The following instructions are based on the instructions for Tomcat-5.x, available at http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html which is current at the time this document was written.

First, install the .jar file that comes with Connector/J in $CATALINA_HOME/common/lib so that it is available to all applications installed in the container.

Next, configure the JNDI DataSource by adding a declaration resource to $CATALINA_HOME/conf/server.xml in the context that defines your web application:

  <Context ....>

  ...

  <Resource name="jdbc/MySQLDB"
               auth="Container"
               type="javax.sql.DataSource"/>

  <ResourceParams name="jdbc/MySQLDB">
    <parameter>
      <name>factory</name>
      <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
    </parameter>

    <parameter>
      <name>maxActive</name>
      <value>10</value>
    </parameter>

    <parameter>
      <name>maxIdle</name>
      <value>5</value>
    </parameter>

    <parameter>
      <name>validationQuery</name>
      <value>SELECT 1</value>
    </parameter>

    <parameter>
      <name>testOnBorrow</name>
      <value>true</value>
    </parameter>

    <parameter>
      <name>testWhileIdle</name>
      <value>true</value>
    </parameter>

    <parameter>
      <name>timeBetweenEvictionRunsMillis</name>
      <value>10000</value>
    </parameter>

    <parameter>
      <name>minEvictableIdleTimeMillis</name>
      <value>60000</value>
    </parameter>

    <parameter>
     <name>username</name>
     <value>someuser</value>
    </parameter>

    <parameter>
     <name>password</name>
     <value>somepass</value>
    </parameter>

    <parameter>
       <name>driverClassName</name>
       <value>com.mysql.cj.jdbc.Driver</value>
    </parameter>

    <parameter>
      <name>url</name>
      <value>jdbc:mysql://localhost:3306/test</value>
    </parameter>

  </ResourceParams>
</Context>

Connector/J introduces a facility whereby, rather than use a validationQuery value of SELECT 1, it is possible to use validationQuery with a value set to /* ping */. This sends a ping to the server which then returns a fake result set. This is a lighter weight solution. It also has the advantage that if using ReplicationConnection or LoadBalancedConnection type connections, the ping will be sent across all active connections. The following XML snippet illustrates how to select this option:

<parameter>
 <name>validationQuery</name>
 <value>/* ping */</value>
</parameter>

Note that /* ping */ has to be specified exactly.

In general, follow the installation instructions that come with your version of Tomcat, as the way you configure datasources in Tomcat changes from time to time, and if you use the wrong syntax in your XML file, you will most likely end up with an exception similar to the following:

Error: java.sql.SQLException: Cannot load JDBC driver class 'null ' SQL
state: null

Note that the auto-loading of drivers having the META-INF/service/java.sql.Driver class in JDBC 4.0 and later causes an improper undeployment of the Connector/J driver in Tomcat on Windows. Namely, the Connector/J jar remains locked. This is an initialization problem that is not related to the driver. The possible workarounds, if viable, are as follows: use "antiResourceLocking=true" as a Tomcat Context attribute, or remove the META-INF/ directory.

Chapter 12 Using Connector/J with JBoss

These instructions cover JBoss-4.x. To make the JDBC driver classes available to the application server, copy the .jar file that comes with Connector/J to the lib directory for your server configuration (which is usually called default). Then, in the same configuration directory, in the subdirectory named deploy, create a datasource configuration file that ends with -ds.xml, which tells JBoss to deploy this file as a JDBC Datasource. The file should have the following contents:

<datasources>
    <local-tx-datasource>

        <jndi-name>MySQLDB</jndi-name>
        <connection-url>jdbc:mysql://localhost:3306/dbname</connection-url>
        <driver-class>com.mysql.cj.jdbc.Driver</driver-class>
        <user-name>user</user-name>
        <password>pass</password>

        <min-pool-size>5</min-pool-size>

        <max-pool-size>20</max-pool-size>

        <idle-timeout-minutes>5</idle-timeout-minutes>

        <exception-sorter-class-name>
  com.mysql.cj.jdbc.integration.jboss.ExtendedMysqlExceptionSorter
        </exception-sorter-class-name>
        <valid-connection-checker-class-name>
  com.mysql.cj.jdbc.integration.jboss.MysqlValidConnectionChecker
        </valid-connection-checker-class-name>

    </local-tx-datasource>
</datasources>

Chapter 13 Using Connector/J with Spring

Table of Contents

13.1 Using JdbcTemplate

13.2 Transactional JDBC Access

13.3 Connection Pooling with Spring

The Spring Framework is a Java-based application framework designed for assisting in application design by providing a way to configure components. The technique used by Spring is a well known design pattern called Dependency Injection (see Inversion of Control Containers and the Dependency Injection pattern). This article will focus on Java-oriented access to MySQL databases with Spring 2.0. For those wondering, there is a .NET port of Spring appropriately named Spring.NET.

Spring is not only a system for configuring components, but also includes support for aspect oriented programming (AOP). This is one of the main benefits and the foundation for Spring's resource and transaction management. Spring also provides utilities for integrating resource management with JDBC and Hibernate.

For the examples in this section the MySQL world sample database will be used. The first task is to set up a MySQL data source through Spring. Components within Spring use the “bean” terminology. For example, to configure a connection to a MySQL server supporting the world sample database, you might use:

<util:map id="dbProps">
    <entry key="db.driver" value="com.mysql.cj.jdbc.Driver"/>
    <entry key="db.jdbcurl" value="jdbc:mysql://localhost/world"/>
    <entry key="db.username" value="myuser"/>
    <entry key="db.password" value="mypass"/>
</util:map>

In the above example, we are assigning values to properties that will be used in the configuration. For the datasource configuration:

<bean id="dataSource"
       class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${db.driver}"/>
    <property name="url" value="${db.jdbcurl}"/>
    <property name="username" value="${db.username}"/>
    <property name="password" value="${db.password}"/>
</bean>

The placeholders are used to provide values for properties of this bean. This means that we can specify all the properties of the configuration in one place instead of entering the values for each property on each bean. We do, however, need one more bean to pull this all together. The last bean is responsible for actually replacing the placeholders with the property values.

<bean
 class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="properties" ref="dbProps"/>
</bean>

Now that we have our MySQL data source configured and ready to go, we write some Java code to access it. The example below will retrieve three random cities and their corresponding country using the data source we configured with Spring.

// Create a new application context. this processes the Spring config
ApplicationContext ctx =
    new ClassPathXmlApplicationContext("ex1appContext.xml");
// Retrieve the data source from the application context
    DataSource ds = (DataSource) ctx.getBean("dataSource");
// Open a database connection using Spring's DataSourceUtils
Connection c = DataSourceUtils.getConnection(ds);
try {
    // retrieve a list of three random cities
    PreparedStatement ps = c.prepareStatement(
        "select City.Name as 'City', Country.Name as 'Country' " +
        "from City inner join Country on City.CountryCode = Country.Code " +
        "order by rand() limit 3");
    ResultSet rs = ps.executeQuery();
    while(rs.next()) {
        String city = rs.getString("City");
        String country = rs.getString("Country");
        System.out.printf("The city %s is in %s%n", city, country);
    }
} catch (SQLException ex) {
    // something has failed and we print a stack trace to analyse the error
    ex.printStackTrace();
    // ignore failure closing connection
    try { c.close(); } catch (SQLException e) { }
} finally {
    // properly release our connection
    DataSourceUtils.releaseConnection(c, ds);
}

This is very similar to normal JDBC access to MySQL with the main difference being that we are using DataSourceUtils instead of the DriverManager to create the connection.

While it may seem like a small difference, the implications are somewhat far reaching. Spring manages this resource in a way similar to a container managed data source in a J2EE application server. When a connection is opened, it can be subsequently accessed in other parts of the code if it is synchronized with a transaction. This makes it possible to treat different parts of your application as transactional instead of passing around a database connection.

13.1 Using JdbcTemplate

Spring makes extensive use of the Template method design pattern (see Template Method Pattern). Our immediate focus will be on the JdbcTemplate and related classes, specifically NamedParameterJdbcTemplate. The template classes handle obtaining and releasing a connection for data access when one is needed.

The next example shows how to use NamedParameterJdbcTemplate inside of a DAO (Data Access Object) class to retrieve a random city given a country code.

public class Ex2JdbcDao {
     /**
     * Data source reference which will be provided by Spring.
     */
     private DataSource dataSource;

     /**
     * Our query to find a random city given a country code. Notice
     * the ":country" parameter toward the end. This is called a
     * named parameter.
     */
     private String queryString = "select Name from City " +
        "where CountryCode = :country order by rand() limit 1";

     /**
     * Retrieve a random city using Spring JDBC access classes.
     */
     public String getRandomCityByCountryCode(String cntryCode) {
         // A template that permits using queries with named parameters
         NamedParameterJdbcTemplate template =
         new NamedParameterJdbcTemplate(dataSource);
         // A java.util.Map is used to provide values for the parameters
         Map params = new HashMap();
         params.put("country", cntryCode);
         // We query for an Object and specify what class we are expecting
         return (String)template.queryForObject(queryString, params, String.class);
     }

    /**
    * A JavaBean setter-style method to allow Spring to inject the data source.
    * @param dataSource
    */
    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }
}

The focus in the above code is on the getRandomCityByCountryCode() method. We pass a country code and use the NamedParameterJdbcTemplate to query for a city. The country code is placed in a Map with the key "country", which is the parameter is named in the SQL query.

To access this code, you need to configure it with Spring by providing a reference to the data source.

<bean id="dao" class="code.Ex2JdbcDao">
    <property name="dataSource" ref="dataSource"/>
</bean>

At this point, we can just grab a reference to the DAO from Spring and call getRandomCityByCountryCode().

    // Create the application context
    ApplicationContext ctx =
    new ClassPathXmlApplicationContext("ex2appContext.xml");
    // Obtain a reference to our DAO
    Ex2JdbcDao dao = (Ex2JdbcDao) ctx.getBean("dao");

    String countryCode = "USA";

    // Find a few random cities in the US
    for(int i = 0; i < 4; ++i)
        System.out.printf("A random city in %s is %s%n", countryCode,
            dao.getRandomCityByCountryCode(countryCode));

This example shows how to use Spring's JDBC classes to completely abstract away the use of traditional JDBC classes including Connection and PreparedStatement.

13.2 Transactional JDBC Access

Spring allows us to add transactions into our code without having to deal directly with the JDBC classes. For that purpose, Spring provides a transaction management package that not only replaces JDBC transaction management, but also enables declarative transaction management (configuration instead of code).

To use transactional database access, we will need to change the storage engine of the tables in the world database. The downloaded script explicitly creates MyISAM tables, which do not support transactional semantics. The InnoDB storage engine does support transactions and this is what we will be using. We can change the storage engine with the following statements.

ALTER TABLE City ENGINE=InnoDB;
ALTER TABLE Country ENGINE=InnoDB;
ALTER TABLE CountryLanguage ENGINE=InnoDB;

A good programming practice emphasized by Spring is separating interfaces and implementations. What this means is that we can create a Java interface and only use the operations on this interface without any internal knowledge of what the actual implementation is. We will let Spring manage the implementation and with this it will manage the transactions for our implementation.

First you create a simple interface:

public interface Ex3Dao {
    Integer createCity(String name, String countryCode,
    String district, Integer population);
}

This interface contains one method that will create a new city record in the database and return the id of the new record. Next you need to create an implementation of this interface.

public class Ex3DaoImpl implements Ex3Dao {
    protected DataSource dataSource;
    protected SqlUpdate updateQuery;
    protected SqlFunction idQuery;

    public Integer createCity(String name, String countryCode,
        String district, Integer population) {
            updateQuery.update(new Object[] { name, countryCode,
                   district, population });
            return getLastId();
        }

    protected Integer getLastId() {
        return idQuery.run();
    }
}

You can see that we only operate on abstract query objects here and do not deal directly with the JDBC API. Also, this is the complete implementation. All of our transaction management will be dealt with in the configuration. To get the configuration started, we need to create the DAO.

<bean id="dao" class="code.Ex3DaoImpl">
    <property name="dataSource" ref="dataSource"/>
    <property name="updateQuery">...</property>
    <property name="idQuery">...</property>
</bean>

Now we need to set up the transaction configuration. The first thing we must do is create transaction manager to manage the data source and a specification of what transaction properties are required for the dao methods.

<bean id="transactionManager"
  class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
</bean>

<tx:advice id="txAdvice" transaction-manager="transactionManager">
    <tx:attributes>
        <tx:method name="*"/>
    </tx:attributes>
</tx:advice>

The preceding code creates a transaction manager that handles transactions for the data source provided to it. The txAdvice uses this transaction manager and the attributes specify to create a transaction for all methods. Finally we need to apply this advice with an AOP pointcut.

<aop:config>
    <aop:pointcut id="daoMethods"
        expression="execution(* code.Ex3Dao.*(..))"/>
     <aop:advisor advice-ref="txAdvice" pointcut-ref="daoMethods"/>
</aop:config>

This basically says that all methods called on the Ex3Dao interface will be wrapped in a transaction. To make use of this, we only have to retrieve the dao from the application context and call a method on the dao instance.

Ex3Dao dao = (Ex3Dao) ctx.getBean("dao");
Integer id = dao.createCity(name,  countryCode, district, pop);

We can verify from this that there is no transaction management happening in our Java code and it is all configured with Spring. This is a very powerful notion and regarded as one of the most beneficial features of Spring.

13.3 Connection Pooling with Spring

In many situations, such as web applications, there will be a large number of small database transactions. When this is the case, it usually makes sense to create a pool of database connections available for web requests as needed. Although MySQL does not spawn an extra process when a connection is made, there is still a small amount of overhead to create and set up the connection. Pooling of connections also alleviates problems such as collecting large amounts of sockets in the TIME_WAIT state.

Setting up pooling of MySQL connections with Spring is as simple as changing the data source configuration in the application context. There are a number of configurations that we can use. The first example is based on the Jakarta Commons DBCP library. The example below replaces the source configuration that was based on DriverManagerDataSource with DBCP's BasicDataSource.

<bean id="dataSource" destroy-method="close"
  class="org.apache.commons.dbcp.BasicDataSource">
    <property name="driverClassName" value="${db.driver}"/>
    <property name="url" value="${db.jdbcurl}"/>
    <property name="username" value="${db.username}"/>
    <property name="password" value="${db.password}"/>
    <property name="initialSize" value="3"/>
</bean>

The configuration of the two solutions is very similar. The difference is that DBCP will pool connections to the database instead of creating a new connection every time one is requested. We have also set a parameter here called initialSize. This tells DBCP that we want three connections in the pool when it is created.

Another way to configure connection pooling is to configure a data source in our J2EE application server. Using JBoss as an example, you can set up the MySQL connection pool by creating a file called mysql-local-ds.xml and placing it in the server/default/deploy directory in JBoss. Once we have this setup, we can use JNDI to look it up. With Spring, this lookup is very simple. The data source configuration looks like this.

<jee:jndi-lookup id="dataSource" jndi-name="java:MySQL_DS"/>

Chapter 14 Using Connector/J with MySQL Fabric

MySQL Fabric is a system for managing a farm of MySQL servers (and other components). Fabric provides an extensible and easy to use system for managing a MySQL deployment for sharding and high-availability.

For more information on MySQL Fabric, see MySQL Fabric. For instructions on how to use Connector/J with MySQL Fabric, see Using Connector/J with MySQL Fabric.

Chapter 15 Troubleshooting Connector/J Applications

This section explains the symptoms and resolutions for the most commonly encountered issues with applications using MySQL Connector/J.

Questions

15.1: When I try to connect to the database with MySQL Connector/J, I get the following exception:

SQLException: Server configuration denies access to data source
SQLState: 08001
VendorError: 0

What is going on? I can connect just fine with the MySQL command-line client.

15.2: My application throws an SQLException 'No Suitable Driver'. Why is this happening?

15.3: I'm trying to use MySQL Connector/J in an applet or application and I get an exception similar to:

SQLException: Cannot connect to MySQL server on host:3306.
Is there a MySQL server running on the machine/port you
are trying to connect to?

(java.security.AccessControlException)
SQLState: 08S01
VendorError: 0

15.4: I have a servlet/application that works fine for a day, and then stops working overnight

15.5: I cannot connect to the MySQL server using Connector/J, and I'm sure the connection parameters are correct.

15.6: My application is deployed through JBoss and I am using transactions to handle the statements on the MySQL database. Under heavy loads, I am getting an error and stack trace, but these only occur after a fixed period of heavy activity.

15.7: Updating a table that contains a primary key that is either FLOAT or compound primary key that uses FLOAT fails to update the table and raises an exception.

15.8: I get an ER_NET_PACKET_TOO_LARGE exception, even though the binary blob size I want to insert using JDBC is safely below the max_allowed_packet size.

15.9: What should I do if I receive error messages similar to the following: “Communications link failure – Last packet sent to the server was X ms ago”?

15.10: Why does Connector/J not reconnect to MySQL and re-issue the statement after a communication failure instead of throwing an Exception, even though I use the autoReconnect connection string option?

15.11: How can I use 3-byte UTF8 with Connector/J?

15.12: How can I use 4-byte UTF8, utf8mb4 with Connector/J?

15.13: Using useServerPrepStmts=false and certain character encodings can lead to corruption when inserting BLOBs. How can this be avoided?

Questions and Answers

15.1: When I try to connect to the database with MySQL Connector/J, I get the following exception:

SQLException: Server configuration denies access to data source
SQLState: 08001
VendorError: 0

What is going on? I can connect just fine with the MySQL command-line client.

MySQL Connector/J must use TCP/IP sockets to connect to MySQL, as Java does not support Unix Domain Sockets. Therefore, when MySQL Connector/J connects to MySQL, the security manager in MySQL server will use its grant tables to determine whether the connection is permitted.

You must add the necessary security credentials to the MySQL server for this to happen, using the GRANT statement to your MySQL Server. See GRANT Syntax, for more information.

Note

Testing your connectivity with the mysql command-line client will not work unless you add the "host" flag, and use something other than localhost for the host. The mysql command-line client will use Unix domain sockets if you use the special host name localhost. If you are testing connectivity to localhost, use 127.0.0.1 as the host name instead.

Warning

Changing privileges and permissions improperly in MySQL can potentially cause your server installation to not have optimal security properties.

15.2: My application throws an SQLException 'No Suitable Driver'. Why is this happening?

There are three possible causes for this error:

The Connector/J driver is not in your CLASSPATH, see Chapter 4, Connector/J Installation.

The format of your connection URL is incorrect, or you are referencing the wrong JDBC driver.

When using DriverManager, the jdbc.drivers system property has not been populated with the location of the Connector/J driver.

15.3: I'm trying to use MySQL Connector/J in an applet or application and I get an exception similar to:

SQLException: Cannot connect to MySQL server on host:3306.
Is there a MySQL server running on the machine/port you
are trying to connect to?

(java.security.AccessControlException)
SQLState: 08S01
VendorError: 0

Either you're running an Applet, your MySQL server has been installed with the "skip-networking" option set, or your MySQL server has a firewall sitting in front of it.

Applets can only make network connections back to the machine that runs the web server that served the .class files for the applet. This means that MySQL must run on the same machine (or you must have some sort of port re-direction) for this to work. This also means that you will not be able to test applets from your local file system, you must always deploy them to a web server.

MySQL Connector/J can only communicate with MySQL using TCP/IP, as Java does not support Unix domain sockets. TCP/IP communication with MySQL might be affected if MySQL was started with the "skip-networking" flag, or if it is firewalled.

If MySQL has been started with the "skip-networking" option set (the Debian Linux package of MySQL server does this for example), you need to comment it out in the file /etc/mysql/my.cnf or /etc/my.cnf. Of course your my.cnf file might also exist in the data directory of your MySQL server, or anywhere else (depending on how MySQL was compiled for your system). Binaries created by us always look in /etc/my.cnf and datadir/my.cnf. If your MySQL server has been firewalled, you will need to have the firewall configured to allow TCP/IP connections from the host where your Java code is running to the MySQL server on the port that MySQL is listening to (by default, 3306).

15.4: I have a servlet/application that works fine for a day, and then stops working overnight

MySQL closes connections after 8 hours of inactivity. You either need to use a connection pool that handles stale connections or use the autoReconnect parameter (see Section 6.1, “Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J”).

Also, catch SQLExceptions in your application and deal with them, rather than propagating them all the way until your application exits. This is just good programming practice. MySQL Connector/J will set the SQLState (see java.sql.SQLException.getSQLState() in your API docs) to 08S01 when it encounters network-connectivity issues during the processing of a query. Attempt to reconnect to MySQL at this point.

The following (simplistic) example shows what code that can handle these exceptions might look like:

Example 15.1 Connector/J: Example of transaction with retry logic

public void doBusinessOp() throws SQLException {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;

    //
    // How many times do you want to retry the transaction
    // (or at least _getting_ a connection)?
    //
    int retryCount = 5;

    boolean transactionCompleted = false;

    do {
        try {
            conn = getConnection(); // assume getting this from a
                                    // javax.sql.DataSource, or the
                                    // java.sql.DriverManager

            conn.setAutoCommit(false);

            //
            // Okay, at this point, the 'retry-ability' of the
            // transaction really depends on your application logic,
            // whether or not you're using autocommit (in this case
            // not), and whether you're using transactional storage
            // engines
            //
            // For this example, we'll assume that it's _not_ safe
            // to retry the entire transaction, so we set retry
            // count to 0 at this point
            //
            // If you were using exclusively transaction-safe tables,
            // or your application could recover from a connection going
            // bad in the middle of an operation, then you would not
            // touch 'retryCount' here, and just let the loop repeat
            // until retryCount == 0.
            //
            retryCount = 0;

            stmt = conn.createStatement();

            String query = "SELECT foo FROM bar ORDER BY baz";

            rs = stmt.executeQuery(query);

            while (rs.next()) {
            }

            rs.close();
            rs = null;

            stmt.close();
            stmt = null;

            conn.commit();
            conn.close();
            conn = null;

            transactionCompleted = true;
        } catch (SQLException sqlEx) {

            //
            // The two SQL states that are 'retry-able' are 08S01
            // for a communications error, and 40001 for deadlock.
            //
            // Only retry if the error was due to a stale connection,
            // communications problem or deadlock
            //

            String sqlState = sqlEx.getSQLState();

            if ("08S01".equals(sqlState) || "40001".equals(sqlState)) {
                retryCount -= 1;
            } else {
                retryCount = 0;
            }
        } finally {
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException sqlEx) {
                    // You'd probably want to log this...
                }
            }

            if (stmt != null) {
                try {
                    stmt.close();
                } catch (SQLException sqlEx) {
                    // You'd probably want to log this as well...
                }
            }

            if (conn != null) {
                try {
                    //
                    // If we got here, and conn is not null, the
                    // transaction should be rolled back, as not
                    // all work has been done

                    try {
                        conn.rollback();
                    } finally {
                        conn.close();
                    }
                } catch (SQLException sqlEx) {
                    //
                    // If we got an exception here, something
                    // pretty serious is going on, so we better
                    // pass it up the stack, rather than just
                    // logging it...

                    throw sqlEx;
                }
            }
        }
    } while (!transactionCompleted && (retryCount > 0));
}

Note

Use of the autoReconnect option is not recommended because there is no safe method of reconnecting to the MySQL server without risking some corruption of the connection state or database state information. Instead, use a connection pool, which will enable your application to connect to the MySQL server using an available connection from the pool. The autoReconnect facility is deprecated, and may be removed in a future release.

15.5: I cannot connect to the MySQL server using Connector/J, and I'm sure the connection parameters are correct.

Make sure that the skip-networking option has not been enabled on your server. Connector/J must be able to communicate with your server over TCP/IP; named sockets are not supported. Also ensure that you are not filtering connections through a firewall or other network security system. For more information, see Can't connect to [local] MySQL server.

15.6: My application is deployed through JBoss and I am using transactions to handle the statements on the MySQL database. Under heavy loads, I am getting an error and stack trace, but these only occur after a fixed period of heavy activity.

This is a JBoss, not Connector/J, issue and is connected to the use of transactions. Under heavy loads the time taken for transactions to complete can increase, and the error is caused because you have exceeded the predefined timeout.

You can increase the timeout value by setting the TransactionTimeout attribute to the TransactionManagerService within the /conf/jboss-service.xml file (pre-4.0.3) or /deploy/jta-service.xml for JBoss 4.0.3 or later. See TransactionTimeout within the JBoss wiki for more information.

15.7: Updating a table that contains a primary key that is either FLOAT or compound primary key that uses FLOAT fails to update the table and raises an exception.

Connector/J adds conditions to the WHERE clause during an UPDATE to check the old values of the primary key. If there is no match, then Connector/J considers this a failure condition and raises an exception.

The problem is that rounding differences between supplied values and the values stored in the database may mean that the values never match, and hence the update fails. The issue will affect all queries, not just those from Connector/J.

To prevent this issue, use a primary key that does not use FLOAT. If you have to use a floating point column in your primary key, use DOUBLE or DECIMAL types in place of FLOAT.

15.8: I get an ER_NET_PACKET_TOO_LARGE exception, even though the binary blob size I want to insert using JDBC is safely below the max_allowed_packet size.

This is because the hexEscapeBlock() method in com.mysql.cj.jdbc.PreparedStatement.streamToBytes() may almost double the size of your data.

15.9: What should I do if I receive error messages similar to the following: “Communications link failure – Last packet sent to the server was X ms ago”?

Generally speaking, this error suggests that the network connection has been closed. There can be several root causes:

Firewalls or routers may clamp down on idle connections (the MySQL client/server protocol does not ping).

The MySQL Server may be closing idle connections that exceed the wait_timeout or interactive_timeout threshold.

Although network connections can be volatile, the following can be helpful in avoiding problems:

Ensure connections are valid when used from the connection pool. Use a query that starts with /* ping */ to execute a lightweight ping instead of full query. Note, the syntax of the ping needs to be exactly as specified here.

Minimize the duration a connection object is left idle while other application logic is executed.

Explicitly validate the connection before using it if the connection has been left idle for an extended period of time.

Ensure that wait_timeout and interactive_timeout are set sufficiently high.

Ensure that tcpKeepalive is enabled.

Ensure that any configurable firewall or router timeout settings allow for the maximum expected connection idle time.

Note

Do not expect to be able to reuse a connection without problems if it has being lying idle for a period. If a connection is to be reused after being idle for any length of time, ensure that you explicitly test it before reusing it.

15.10: Why does Connector/J not reconnect to MySQL and re-issue the statement after a communication failure instead of throwing an Exception, even though I use the autoReconnect connection string option?

There are several reasons for this. The first is transactional integrity. The MySQL Reference Manual states that “there is no safe method of reconnecting to the MySQL server without risking some corruption of the connection state or database state information”. Consider the following series of statements for example:

conn.createStatement().execute(
  "UPDATE checking_account SET balance = balance - 1000.00 WHERE customer='Smith'");
conn.createStatement().execute(
  "UPDATE savings_account SET balance = balance + 1000.00 WHERE customer='Smith'");
conn.commit();

Consider the case where the connection to the server fails after the UPDATE to checking_account. If no exception is thrown, and the application never learns about the problem, it will continue executing. However, the server did not commit the first transaction in this case, so that will get rolled back. But execution continues with the next transaction, and increases the savings_account balance by 1000. The application did not receive an exception, so it continued regardless, eventually committing the second transaction, as the commit only applies to the changes made in the new connection. Rather than a transfer taking place, a deposit was made in this example.

Note that running with autocommit enabled does not solve this problem. When Connector/J encounters a communication problem, there is no means to determine whether the server processed the currently executing statement or not. The following theoretical states are equally possible:

The server never received the statement, and therefore no related processing occurred on the server.

The server received the statement, executed it in full, but the response was not received by the client.

If you are running with autocommit enabled, it is not possible to guarantee the state of data on the server when a communication exception is encountered. The statement may have reached the server, or it may not. All you know is that communication failed at some point, before the client received confirmation (or data) from the server. This does not only affect autocommit statements though. If the communication problem occurred during Connection.commit(), the question arises of whether the transaction was committed on the server before the communication failed, or whether the server received the commit request at all.

The second reason for the generation of exceptions is that transaction-scoped contextual data may be vulnerable, for example:

Temporary tables.

User-defined variables.

Server-side prepared statements.

These items are lost when a connection fails, and if the connection silently reconnects without generating an exception, this could be detrimental to the correct execution of your application.

In summary, communication errors generate conditions that may well be unsafe for Connector/J to simply ignore by silently reconnecting. It is necessary for the application to be notified. It is then for the application developer to decide how to proceed in the event of connection errors and failures.

15.11: How can I use 3-byte UTF8 with Connector/J?

To use 3-byte UTF8 with Connector/J set characterEncoding=utf8 and set useUnicode=true in the connection string.

15.12: How can I use 4-byte UTF8, utf8mb4 with Connector/J?

To use 4-byte UTF8 with Connector/J configure the MySQL server with character_set_server=utf8mb4. Connector/J will then use that setting as long as characterEncoding has not been set in the connection string. This is equivalent to autodetection of the character set.

15.13: Using useServerPrepStmts=false and certain character encodings can lead to corruption when inserting BLOBs. How can this be avoided?

When using certain character encodings, such as SJIS, CP932, and BIG5, it is possible that BLOB data contains characters that can be interpreted as control characters, for example, backslash, '\'. This can lead to corrupted data when inserting BLOBs into the database. There are two things that need to be done to avoid this:

Set the connection string option useServerPrepStmts to true.

Set SQL_MODE to NO_BACKSLASH_ESCAPES.

Chapter 16 Connector/J Support

Table of Contents

16.1 Connector/J Community Support

16.2 How to Report Connector/J Bugs or Problems

16.1 Connector/J Community Support

Oracle provides assistance to the user community by means of its mailing lists. For Connector/J related issues, you can get help from experienced users by using the MySQL and Java mailing list. Archives and subscription information is available online at http://lists.mysql.com/java.

For information about subscribing to MySQL mailing lists or to browse list archives, visit http://lists.mysql.com/. See MySQL Mailing Lists.

Community support from experienced users is also available through the JDBC Forum. You may also find help from other users in the other MySQL Forums, located at http://forums.mysql.com. See MySQL Community Support at the MySQL Forums.

16.2 How to Report Connector/J Bugs or Problems

The normal place to report bugs is http://bugs.mysql.com/, which is the address for our bugs database. This database is public, and can be browsed and searched by anyone. If you log in to the system, you will also be able to enter new reports.

If you find a sensitive security bug in MySQL Server, please let us know immediately by sending an email message to <secalert_us@oracle.com>. Exception: Support customers should report all problems, including security bugs, to Oracle Support at http://support.oracle.com/.

Writing a good bug report takes patience, but doing it right the first time saves time both for us and for yourself. A good bug report, containing a full test case for the bug, makes it very likely that we will fix the bug in the next release.

This section will help you write your report correctly so that you do not waste your time doing things that may not help us much or at all.

If you have a repeatable bug report, please report it to the bugs database at http://bugs.mysql.com/. Any bug that we are able to repeat has a high chance of being fixed in the next MySQL release.

To report other problems, you can use one of the MySQL mailing lists.

Remember that it is possible for us to respond to a message containing too much information, but not to one containing too little. People often omit facts because they think they know the cause of a problem and assume that some details do not matter.

A good principle is this: If you are in doubt about stating something, state it. It is faster and less troublesome to write a couple more lines in your report than to wait longer for the answer if we must ask you to provide information that was missing from the initial report.

The most common errors made in bug reports are (a) not including the version number of Connector/J or MySQL used, and (b) not fully describing the platform on which Connector/J is installed (including the JVM version, and the platform type and version number that MySQL itself is installed on).

This is highly relevant information, and in 99 cases out of 100, the bug report is useless without it. Very often we get questions like, “Why doesn't this work for me?” Then we find that the feature requested was not implemented in that MySQL version, or that a bug described in a report has already been fixed in newer MySQL versions.

Sometimes the error is platform-dependent; in such cases, it is next to impossible for us to fix anything without knowing the operating system and the version number of the platform.

If at all possible, create a repeatable, standalone testcase that doesn't involve any third-party classes.

To streamline this process, we ship a base class for testcases with Connector/J, named 'com.mysql.cj.jdbc.util.BaseBugReport'. To create a testcase for Connector/J using this class, create your own class that inherits from com.mysql.cj.jdbc.util.BaseBugReport and override the methods setUp(), tearDown() and runTest().

In the setUp() method, create code that creates your tables, and populates them with any data needed to demonstrate the bug.

In the runTest() method, create code that demonstrates the bug using the tables and data you created in the setUp method.

In the tearDown() method, drop any tables you created in the setUp() method.

In any of the above three methods, use one of the variants of the getConnection() method to create a JDBC connection to MySQL:

getConnection() - Provides a connection to the JDBC URL specified in getUrl(). If a connection already exists, that connection is returned, otherwise a new connection is created.

getNewConnection() - Use this if you need to get a new connection for your bug report (that is, there is more than one connection involved).

getConnection(String url) - Returns a connection using the given URL.

getConnection(String url, Properties props) - Returns a connection using the given URL and properties.

If you need to use a JDBC URL that is different from 'jdbc:mysql:///test', override the method getUrl() as well.

Use the assertTrue(boolean expression) and assertTrue(String failureMessage, boolean expression) methods to create conditions that must be met in your testcase demonstrating the behavior you are expecting (vs. the behavior you are observing, which is why you are most likely filing a bug report).

Finally, create a main() method that creates a new instance of your testcase, and calls the run method:

public static void main(String[] args) throws Exception {
      new MyBugReport().run();
 }

Once you have finished your testcase, and have verified that it demonstrates the bug you are reporting, upload it with your bug report to http://bugs.mysql.com/.

Index

C

character sets

with Connector/J, Using Character Sets and Unicode

connecting

through JDBC and Connector/J, Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

connection pooling, Connection Pooling with Connector/J, Connection Pooling with Spring

Connector/J

reporting problems, How to Report Connector/J Bugs or Problems

troubleshooting, Troubleshooting Connector/J Applications

E

error codes, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_ABORTING_CONNECTION, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_ACCESS_DENIED_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_BAD_FIELD_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_BAD_HOST_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_BAD_TABLE_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_BLOBS_AND_NO_TERMINATED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_BLOB_CANT_HAVE_DEFAULT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_BLOB_KEY_WITHOUT_LENGTH, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_BLOB_USED_AS_KEY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CANT_DO_THIS_DURING_AN_TRANSACTION, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CANT_DROP_FIELD_OR_KEY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CANT_REMOVE_ALL_FIELDS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CANT_USE_OPTION_HERE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CHECK_NOT_IMPLEMENTED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CHECK_NO_SUCH_TABLE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_COLLATION_CHARSET_MISMATCH, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_COLUMNACCESS_DENIED_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CONNECT_TO_MASTER, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_CON_COUNT_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_DBACCESS_DENIED_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_DERIVED_MUST_HAVE_ALIAS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_DUP_ENTRY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_DUP_FIELDNAME, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_DUP_KEY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_DUP_KEYNAME, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_DUP_UNIQUE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_EMPTY_QUERY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_FIELD_SPECIFIED_TWICE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_FORCING_CLOSE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_GRANT_WRONG_HOST_OR_USER, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_HANDSHAKE_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_HOST_IS_BLOCKED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_HOST_NOT_PRIVILEGED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_ILLEGAL_GRANT_FOR_TABLE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_ILLEGAL_REFERENCE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_INVALID_DEFAULT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_INVALID_USE_OF_NULL, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_IPSOCK_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_KEY_COLUMN_DOES_NOT_EXITS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_LOCK_DEADLOCK, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_LOCK_WAIT_TIMEOUT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_MASTER_NET_READ, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_MASTER_NET_WRITE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_MIX_OF_GROUP_FUNC_AND_FIELDS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_MULTIPLE_PRI_KEY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_ERROR_ON_WRITE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_FCNTL_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_PACKETS_OUT_OF_ORDER, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_PACKET_TOO_LARGE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_READ_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_READ_ERROR_FROM_PIPE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_READ_INTERRUPTED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_UNCOMPRESS_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NET_WRITE_INTERRUPTED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NEW_ABORTING_CONNECTION, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NONEXISTING_GRANT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NONEXISTING_TABLE_GRANT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NONUNIQ_TABLE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NON_UNIQ_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NOT_ALLOWED_COMMAND, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NOT_SUPPORTED_AUTH_MODE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NOT_SUPPORTED_YET, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NO_DEFAULT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NO_PERMISSION_TO_CREATE_USER, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NO_REFERENCED_ROW, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NO_SUCH_INDEX, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NO_SUCH_TABLE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_NULL_COLUMN_IN_INDEX, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_OPERAND_COLUMNS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_OUTOFMEMORY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_OUT_OF_SORTMEMORY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_PARSE_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_PASSWORD_ANONYMOUS_USER, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_PASSWORD_NOT_ALLOWED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_PASSWORD_NO_MATCH, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_PRIMARY_CANT_HAVE_NULL, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_READ_ONLY_TRANSACTION, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_REGEXP_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_REQUIRES_PRIMARY_KEY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_ROW_IS_REFERENCED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_SELECT_REDUCED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_SERVER_SHUTDOWN, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_SPATIAL_CANT_HAVE_NULL, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_SUBQUERY_NO_1_ROW, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_SYNTAX_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TABLEACCESS_DENIED_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TABLENAME_NOT_ALLOWED_HERE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TABLE_CANT_HANDLE_AUTO_INCREMENT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TABLE_CANT_HANDLE_BLOB, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TABLE_EXISTS_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TABLE_MUST_HAVE_COLUMNS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_BIG_FIELDLENGTH, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_BIG_ROWSIZE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_BIG_SELECT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_LONG_IDENT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_LONG_KEY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_LONG_STRING, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_MANY_KEYS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_MANY_KEY_PARTS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_MANY_ROWS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_TOO_MANY_USER_CONNECTIONS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_UNKNOWN_CHARACTER_SET, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_UNKNOWN_COM_ERROR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_UNKNOWN_PROCEDURE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_UNKNOWN_STORAGE_ENGINE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_UNKNOWN_TABLE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_UNSUPPORTED_EXTENSION, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_USER_LIMIT_REACHED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WARN_DATA_OUT_OF_RANGE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WARN_DATA_TRUNCATED, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WARN_NULL_TO_NOTNULL, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WARN_TOO_FEW_RECORDS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WARN_TOO_MANY_RECORDS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_AUTO_KEY, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_COLUMN_NAME, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_DB_NAME, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_FIELD_SPEC, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_FIELD_TERMINATORS, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_FIELD_WITH_GROUP, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_FK_DEF, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_GROUP_FIELD, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_KEY_COLUMN, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_NAME_FOR_CATALOG, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_NAME_FOR_INDEX, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_OUTER_JOIN, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_PARAMCOUNT_TO_PROCEDURE, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_SUM_SELECT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_TABLE_NAME, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_TYPE_FOR_VAR, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_VALUE_COUNT, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_VALUE_COUNT_ON_ROW, Mapping MySQL Error Numbers to JDBC SQLState Codes

ER_WRONG_VALUE_FOR_VAR, Mapping MySQL Error Numbers to JDBC SQLState Codes

F

failover

Java clients, Configuring Server Failover

I

IPv6 connection

JDBC URLs, Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

J

J2EE

connection pooling, Connection Pooling with Connector/J

load balancing, Configuring Load Balancing with Connector/J

JBoss application server, Using Connector/J with JBoss

JDBC

and MySQL data types, Java, JDBC and MySQL Types

background information for Connector/J, JDBC Concepts

character sets, Using Character Sets and Unicode

CLASSPATH, Installing the Driver and Configuring the CLASSPATH

code examples, Connector/J Examples

compatibility, JDBC API Implementation Notes

configuration properties, Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

driver for MySQL, Overview of MySQL Connector/J

SQLState codes, Mapping MySQL Error Numbers to JDBC SQLState Codes

troubleshooting, Troubleshooting Connector/J Applications

versions supported, Connector/J Versions, and the MySQL and Java Versions They Support

JDBC URLs

alternative format, Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

general format, Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

L

load balancing

with Connector/J, Configuring Load Balancing with Connector/J, Configuring Master/Slave Replication with Connector/J

M

multi-host connections

with Connector/J, Multi-Host Connections

MySQL Fabric, Using Connector/J with MySQL Fabric

P

PAM authentication

with Connector/J, Connecting Using PAM Authentication

R

replication

with Connector/J, Configuring Master/Slave Replication with Connector/J

S

Spring framework, Using Connector/J with Spring

SQLState error codes, Mapping MySQL Error Numbers to JDBC SQLState Codes

SSL, Connecting Securely Using SSL

T

Tomcat application server, Using Connector/J with Tomcat

troubleshooting

Connector/J, Troubleshooting Connector/J Applications

JDBC SQLState codes, Mapping MySQL Error Numbers to JDBC SQLState Codes

U

Unicode

with Connector/J, Using Character Sets and Unicode

useConfigs connection properties, Properties Files for the useConfigs Option