When you start the mysqld server, you can specify program options using any of the methods described in Section 4.2.3, “Specifying Program Options”. The most common methods are to provide options in an option file or on the command line. However, in most cases it is desirable to make sure that the server uses the same options each time it runs. The best way to ensure this is to list them in an option file. See Section 4.2.6, “Using Option Files”. That section also describes option file format and syntax.
mysqld reads options from the
[mysqld] and [server]
groups. mysqld_safe reads options from the
[mysqld], [server],
[mysqld_safe], and
[safe_mysqld] groups.
mysql.server reads options from the
[mysqld] and [mysql.server]
groups.
An embedded MySQL server usually reads options from the
[server], [embedded], and
[
groups, where xxxxx_SERVER]xxxxx is the name of the
application into which the server is embedded.
mysqld accepts many command options. For a brief summary, execute this command:
mysqld --help
To see the full list, use this command:
mysqld --verbose --help
The following list shows some of the most common server options. Additional options are described in other sections:
Options that affect security: See Section 6.1.4, “Security-Related mysqld Options and Variables”.
SSL-related options: See Section 6.4.5, “Command Options for Secure Connections”.
Binary log control options: See Section 5.4.4, “The Binary Log”.
Replication-related options: See Section 17.1.3, “Replication and Binary Logging Options and Variables”.
Options for loading plugins such as pluggable storage engines: See Section 5.5.2, “Installing and Uninstalling Plugins”.
Options specific to particular storage engines: See Section 14.17, “InnoDB Startup Options and System Variables”, Section 15.3.1, “MyISAM Startup Options”, and Section 18.3.3.8.1, “MySQL Server Options for NDB Cluster”.
Some options control the size of buffers or caches. For a given buffer, the server might need to allocate internal data structures. These structures typically are allocated from the total memory allocated to the buffer, and the amount of space required might be platform dependent. This means that when you assign a value to an option that controls a buffer size, the amount of space actually available might differ from the value assigned. In some cases, the amount might be less than the value assigned. It is also possible that the server will adjust a value upward. For example, if you assign a value of 0 to an option for which the minimal value is 1024, the server will set the value to 1024.
Values for buffer sizes, lengths, and stack sizes are given in bytes unless otherwise specified.
Some options take file name values. Unless otherwise specified,
the default file location is the data directory if the value is a
relative path name. To specify the location explicitly, use an
absolute path name. Suppose that the data directory is
/var/mysql/data. If a file-valued option is
given as a relative path name, it will be located under
/var/mysql/data. If the value is an absolute
path name, its location is as given by the path name.
You can also set the values of server system variables at server
startup by using variable names as options. To assign a value to a
server system variable, use an option of the form
--.
For example, var_name=value--key_buffer_size=32M
sets the key_buffer_size variable
to a value of 32MB.
When you assign a value to a variable, MySQL might automatically correct the value to stay within a given range, or adjust the value to the closest permissible value if only certain values are permitted.
To restrict the maximum value to which a system variable can be
set at runtime with the
SET
statement, specify this maximum by using an option of the form
--maximum-
at server startup.
var_name=value
You can change the values of most system variables at runtime with
the SET
statement. See Section 13.7.4.1, “SET Syntax for Variable Assignment”.
Section 5.1.5, “Server System Variables”, provides a full description for all variables, and additional information for setting them at server startup and runtime. For information on changing system variables, see Section 5.1.1, “Configuring the Server”.
--help, -?
| Command-Line Format | --help | ||
Display a short help message and exit. Use both the
--verbose and
--help options to see the full
message.
| Command-Line Format | --allow-suspicious-udfs | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
This option controls whether user-defined functions that have
only an xxx symbol for the main function
can be loaded. By default, the option is off and only UDFs
that have at least one auxiliary symbol can be loaded; this
prevents attempts at loading functions from shared object
files other than those containing legitimate UDFs. See
Section 24.4.2.6, “UDF Security Precautions”.
| Command-Line Format | --ansi | ||
Use standard (ANSI) SQL syntax instead of MySQL syntax. For
more precise control over the server SQL mode, use the
--sql-mode option instead. See
Section 1.7, “MySQL Standards Compliance”, and
Section 5.1.8, “Server SQL Modes”.
--basedir=,
dir_name-b
dir_name
| Command-Line Format | --basedir=dir_name | ||
| System Variable | Name | basedir | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | directory name | |
The path to the MySQL installation directory. All paths are usually resolved relative to this directory.
| Command-Line Format | --big-tables | ||
| System Variable (<= 5.5.2) | Name | big_tables | |
| Variable Scope | Session | ||
| Dynamic Variable | Yes | ||
| System Variable (>= 5.5.3) | Name | big_tables | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
Enable large result sets by saving all temporary sets in files. This option prevents most “table full” errors, but also slows down queries for which in-memory tables would suffice. The server is able to handle large result sets automatically by using memory for small temporary tables and switching to disk tables where necessary.
| Command-Line Format | --bind-address=addr | ||
| Permitted Values | Type | string | |
| Default | 0.0.0.0 | ||
The MySQL server listens on a single network socket for TCP/IP
connections. This socket is bound to a single address, but it
is possible for an address to map onto multiple network
interfaces. The default address is 0.0.0.0.
To specify an address explicitly, use the
--bind-address=
option at server startup, where
addraddr is an IPv4 or IPv6 address or
a host name. (IPv6 addresses are not supported before MySQL
5.5.3.) If addr is a host name, the
server resolves the name to an IP address and binds to that
address.
The server treats different types of addresses as follows:
If the address is 0.0.0.0, the server
accepts TCP/IP connections on all server host IPv4
interfaces.
If the address is ::, the server
accepts TCP/IP connections on all server host IPv4 and
IPv6 interfaces. Use this address to permit both IPv4 and
IPv6 connections on all server interfaces.
If the address is an IPv4-mapped address, the server
accepts TCP/IP connections for that address, in either
IPv4 or IPv6 format. For example, if the server is bound
to ::ffff:127.0.0.1, clients can
connect using --host=127.0.0.1 or
--host=::ffff:127.0.0.1.
If the address is a “regular” IPv4 or IPv6
address (such as 127.0.0.1 or
::1), the server accepts TCP/IP
connections only for that IPv4 or IPv6 address.
If you intend to bind the server to a specific address, be
sure that the mysql.user grant table
contains an account with administrative privileges that you
can use to connect to that address. Otherwise, you will not be
able to shut down the server. For example, if you bind the
server to ::, you can connect to it using
all existing accounts. But if you bind the server to
::1, it accepts connections only on that
address. In that case, first make sure that the
'root'@'::1' account is present in the
mysql.user table so you can still connect
to the server to shut it down.
--binlog-format={ROW|STATEMENT|MIXED}
| Command-Line Format | --binlog-format=format | ||
| System Variable | Name | binlog_format | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | enumeration | |
| Default | STATEMENT | ||
| Valid Values | ROW | ||
STATEMENT | |||
MIXED | |||
| Permitted Values (>= 5.5.15-ndb-7.2.1, <= 5.5.30-ndb-7.2.12) | Type | enumeration | |
| Default | STATEMENT | ||
| Valid Values | ROW | ||
STATEMENT | |||
MIXED | |||
| Permitted Values (>= 5.5.31-ndb-7.2.13) | Type | enumeration | |
| Default | MIXED | ||
| Valid Values | ROW | ||
STATEMENT | |||
MIXED | |||
Specify whether to use row-based, statement-based, or mixed replication. Statement-based is the default in MySQL 5.5. This is also true for MySQL Cluster NDB 7.2.1 and later. See Section 17.1.2, “Replication Formats”.
Under some conditions, changing this variable at runtime is not possible, or causes replication to fail. See Section 5.4.4.2, “Setting The Binary Log Format”, for more information.
Prior to MySQL 5.5, setting the binary logging format without
enabling binary logging prevented the MySQL server from
starting. In MySQL 5.5, the server starts in such
cases, the binlog_format
global system variable is set, and a warning is logged instead
of an error. (Bug #42928)
| Command-Line Format | --bootstrap | ||
This option is used by the mysql_install_db program to create the MySQL privilege tables without having to start a full MySQL server.
When the server operates in bootstap mode, some functionality
is unavailable that limits the statements permitted in any
file named by the --init-file option. For
more information, see the description of that option.
| Command-Line Format | --character-sets-dir=dir_name | ||
| System Variable | Name | character_sets_dir | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | directory name | |
The directory where character sets are installed. See Section 10.5, “Character Set Configuration”.
--character-set-client-handshake
| Command-Line Format | --character-set-client-handshake | ||
| Permitted Values | Type | boolean | |
| Default | TRUE | ||
Do not ignore character set information sent by the client. To
ignore client information and use the default server character
set, use
--skip-character-set-client-handshake;
this makes MySQL behave like MySQL 4.0.
--character-set-filesystem=
charset_name
| Command-Line Format | --character-set-filesystem=name | ||
| System Variable | Name | character_set_filesystem | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | string | |
| Default | binary | ||
The file system character set. This option sets the
character_set_filesystem
system variable.
--character-set-server=,
charset_name-C
charset_name
| Command-Line Format | --character-set-server | ||
| System Variable | Name | character_set_server | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | string | |
| Default | latin1 | ||
Use charset_name as the default
server character set. See
Section 10.5, “Character Set Configuration”. If you use this
option to specify a nondefault character set, you should also
use --collation-server to
specify the collation.
--chroot=,
dir_name-r
dir_name
| Command-Line Format | --chroot=dir_name | ||
| Permitted Values | Type | directory name | |
Put the mysqld server in a closed
environment during startup by using the
chroot() system call. This is a recommended
security measure. Use of this option somewhat limits
LOAD DATA
INFILE and
SELECT ... INTO
OUTFILE.
--collation-server=
collation_name
| Command-Line Format | --collation-server | ||
| System Variable | Name | collation_server | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | string | |
| Default | latin1_swedish_ci | ||
Use collation_name as the default
server collation. See Section 10.5, “Character Set Configuration”.
| Command-Line Format | --console | ||
| Platform Specific | Windows | ||
(Windows only.) Write error log messages to
stderr and stdout.
mysqld does not close the console window if
this option is used.
As of MySQL 5.5.3, if both
--log-error and
--console are specified,
--log-error takes precedence.
The server writes to the log file, but not to the console.
Before 5.5.3, whichever option is given last takes precedence.
| Command-Line Format | --core-file | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
Write a core file if mysqld dies. The name
and location of the core file is system dependent. On Linux, a
core file named
core. is
written to the current working directory of the process, which
for mysqld is the data directory.
pidpid represents the process ID of
the server process. On OS X, a core file named
core. is
written to the pid/cores directory. On
Solaris, use the coreadm command to specify
where to write the core file and how to name it.
For some systems, to get a core file you must also specify the
--core-file-size option to
mysqld_safe. See
Section 4.3.2, “mysqld_safe — MySQL Server Startup Script”. On some systems, such as
Solaris, you do not get a core file if you are also using the
--user option. There might be
additional restrictions or limitations. For example, it might
be necessary to execute ulimit -c unlimited
before starting the server. Consult your system documentation.
--datadir=,
dir_name-h
dir_name
| Command-Line Format | --datadir=dir_name | ||
| System Variable | Name | datadir | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | directory name | |
The path to the data directory.
--debug[=,
debug_options]-# [
debug_options]
| Command-Line Format | --debug[=debug_options] | ||
| System Variable | Name | debug | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values (Unix) | Type | string | |
| Default | d:t:i:o,/tmp/mysqld.trace | ||
| Permitted Values (Windows) | Type | string | |
| Default | d:t:i:O,\mysqld.trace | ||
If MySQL is configured with the
-DWITH_DEBUG=1
CMake option, you can use this option to
get a trace file of what mysqld is doing. A
typical debug_options string is
d:t:o,.
The default is file_named:t:i:o,/tmp/mysqld.trace on
Unix and d:t:i:O,\mysqld.trace on Windows.
Using -DWITH_DEBUG=1 to
configure MySQL with debugging support enables you to use the
--debug="d,parser_debug" option
when you start the server. This causes the Bison parser that
is used to process SQL statements to dump a parser trace to
the server's standard error output. Typically, this output is
written to the error log.
This option may be given multiple times. Values that begin
with + or - are added to
or subtracted from the previous value. For example,
--debug=T
--debug=+P sets the value to
P:T.
For more information, see Section 24.5.3, “The DBUG Package”.
| Command-Line Format | --debug-sync-timeout[=#] | ||
| Permitted Values | Type | integer | |
Controls whether the Debug Sync facility for testing and
debugging is enabled. Use of Debug Sync requires that MySQL be
configured with the
-DENABLE_DEBUG_SYNC=1
CMake option (see
Section 2.9.4, “MySQL Source-Configuration Options”). If Debug Sync
is not compiled in, this option is not available. The option
value is a timeout in seconds. The default value is 0, which
disables Debug Sync. To enable it, specify a value greater
than 0; this value also becomes the default timeout for
individual synchronization points. If the option is given
without a value, the timeout is set to 300 seconds.
For a description of the Debug Sync facility and how to use synchronization points, see MySQL Internals: Test Synchronization.
--default-character-set=
charset_name
| Deprecated | 5.0.0 | ||
| Removed | 5.5.3 | ||
| Command-Line Format | --default-character-set=name | ||
| Permitted Values | Type | string | |
Use charset_name as the default
character set. This option is deprecated in favor of
--character-set-server. See
Section 10.5, “Character Set Configuration”.
--default-character-set was
removed in MySQL 5.5.3.
--default-collation=
collation_name
| Deprecated | 4.1.3 | ||
| Command-Line Format | --default-collation=name | ||
| Permitted Values | Type | string | |
Use collation_name as the default
collation. This option is deprecated in favor of
--collation-server. See
Section 10.5, “Character Set Configuration”.
--default-collation was removed
in MySQL 5.5.3.
| Command-Line Format | --default-storage-engine=name | ||
| System Variable (<= 5.5.2) | Name | storage_engine | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| System Variable (>= 5.5.3) | Name | default_storage_engine | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values (<= 5.5.4) | Type | enumeration | |
| Default | MyISAM | ||
| Permitted Values (>= 5.5.5) | Type | enumeration | |
| Default | InnoDB | ||
Set the default storage engine (table type) for tables. See Chapter 15, Alternative Storage Engines.
If you disable the default storage engine at server startup, you must set the default engine to a different engine or the server will not start.
| Command-Line Format | --default-time-zone=name | ||
| Permitted Values | Type | string | |
Set the default server time zone. This option sets the global
time_zone system variable. If
this option is not given, the default time zone is the same as
the system time zone (given by the value of the
system_time_zone system
variable.
--defaults-extra-file=
file_name
Read this option file after the global option file but (on
Unix) before the user option file. If the file does not exist
or is otherwise inaccessible, an error occurs. Before MySQL
5.5.8, file_name must be the full
path name to the file. As of MySQL 5.5.8, the name is
interpreted relative to the current directory if given as a
relative path name.
Use only the given option file. If the file does not exist or
is otherwise inaccessible, an error occurs. Before MySQL
5.5.8, file_name must be the full
path name to the file. As of MySQL 5.5.8, the name is
interpreted relative to the current directory if given as a
relative path name.
Read not only the usual option groups, but also groups with
the usual names and a suffix of
str. For example,
mysqld normally reads the
[mysqld] group. If the
--defaults-group-suffix=_other
option is given, mysqld also reads the
[mysqld_other] group.
--delay-key-write[={OFF|ON|ALL}]
| Command-Line Format | --delay-key-write[=name] | ||
| System Variable | Name | delay_key_write | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | enumeration | |
| Default | ON | ||
| Valid Values | ON | ||
OFF | |||
ALL | |||
Specify how to use delayed key writes. Delayed key writing
causes key buffers not to be flushed between writes for
MyISAM tables. OFF
disables delayed key writes. ON enables
delayed key writes for those tables that were created with the
DELAY_KEY_WRITE option.
ALL delays key writes for all
MyISAM tables. See
Section 5.1.1, “Configuring the Server”, and
Section 15.3.1, “MyISAM Startup Options”.
If you set this variable to ALL, you
should not use MyISAM tables from within
another program (such as another MySQL server or
myisamchk) when the tables are in use.
Doing so leads to index corruption.
| Command-Line Format | --des-key-file=file_name | ||
Read the default DES keys from this file. These keys are used
by the DES_ENCRYPT() and
DES_DECRYPT() functions.
This option is deprecated and was removed in MySQL 5.5.3. Use
--external-locking instead.
| Command-Line Format | --enable-named-pipe | ||
| Platform Specific | Windows | ||
Enable support for named pipes. This option applies only on Windows.
| Deprecated | 5.1.54 | ||
| Removed | 5.5.7 | ||
| Command-Line Format | --enable-pstack | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
This option is nonfunctional before MySQL 5.5.7 and removed in 5.5.7.
--engine-condition-pushdown={ON|OFF}
| Deprecated | 5.5.3, by optimizer_switch | ||
| Command-Line Format | --engine-condition-pushdown | ||
| System Variable | Name | engine_condition_pushdown | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | ON | ||
Sets the
engine_condition_pushdown
system variable. For more information, see
Section 8.2.1.5, “Engine Condition Pushdown Optimization”.
| Command-Line Format | --event-scheduler[=value] | ||
| System Variable | Name | event_scheduler | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | enumeration | |
| Default | OFF | ||
| Valid Values | ON | ||
OFF | |||
DISABLED | |||
Enable or disable, and start or stop, the event scheduler.
For detailed information, see
The
--event-scheduler Option.
--exit-info[=,
flags]-T [
flags]
| Command-Line Format | --exit-info[=flags] | ||
| Permitted Values | Type | integer | |
This is a bit mask of different flags that you can use for debugging the mysqld server. Do not use this option unless you know exactly what it does!
| Command-Line Format | --external-locking | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
Enable external locking (system locking), which is disabled by
default. If you use this option on a system on which
lockd does not fully work (such as Linux),
it is easy for mysqld to deadlock.
To disable external locking explicitly, use
--skip-external-locking.
External locking affects only
MyISAM table access. For more
information, including conditions under which it can and
cannot be used, see Section 8.11.5, “External Locking”.
| Command-Line Format | --flush | ||
| System Variable | Name | flush | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
Flush (synchronize) all changes to disk after each SQL statement. Normally, MySQL does a write of all changes to disk only after each SQL statement and lets the operating system handle the synchronizing to disk. See Section B.5.3.3, “What to Do If MySQL Keeps Crashing”.
| Command-Line Format | --gdb | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
Install an interrupt handler for SIGINT
(needed to stop mysqld with
^C to set breakpoints) and disable stack
tracing and core file handling. See Section 24.5, “Debugging and Porting MySQL”.
| Command-Line Format | --general-log | ||
| System Variable | Name | general_log | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
Specify the initial general query log state. With no argument
or an argument of 1, the
--general-log option enables
the log. If omitted or given with an argument of 0, the option
disables the log.
| Command-Line Format | --init-file=file_name | ||
| System Variable | Name | init_file | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | file name | |
Read SQL statements from this file at startup. Each statement must be on a single line and should not include comments.
If the server is started with the
--bootstrap option, it operates
in bootstap mode and some functionality is unavailable that
limits the statements permitted in the file. These include
statements that relate to account management (such as
CREATE USER or
GRANT).
--innodb-
xxx
Set an option for the InnoDB storage
engine. The InnoDB options are listed in
Section 14.17, “InnoDB Startup Options and System Variables”.
| Command-Line Format | --install [service_name] | ||
| Platform Specific | Windows | ||
(Windows only) Install the server as a Windows service that
starts automatically during Windows startup. The default
service name is MySQL if no
service_name value is given. For
more information, see Section 2.3.7.7, “Starting MySQL as a Windows Service”.
If the server is started with the
--defaults-file and
--install options,
--install must be first.
--install-manual
[
service_name]
| Command-Line Format | --install-manual [service_name] | ||
| Platform Specific | Windows | ||
(Windows only) Install the server as a Windows service that
must be started manually. It does not start automatically
during Windows startup. The default service name is
MySQL if no
service_name value is given. For
more information, see Section 2.3.7.7, “Starting MySQL as a Windows Service”.
If the server is started with the
--defaults-file and
--install-manual options,
--install-manual must be
first.
--language=
lang_name,
-L lang_name
| Deprecated | 5.5.0, by lc-messages-dir | ||
| Command-Line Format | --language=name | ||
| System Variable | Name | language | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | directory name | |
| Default | /usr/local/mysql/share/mysql/english/ | ||
The language to use for error messages.
lang_name can be given as the
language name or as the full path name to the directory where
the language files are installed. See
Section 10.2, “Setting the Error Message Language”.
As of MySQL 5.5,
--lc-messages-dir and
--lc-messages should be used
rather than --language, which
is deprecated and handled as an alias for
--lc-messages-dir.
| Command-Line Format | --large-pages | ||
| System Variable | Name | large_pages | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Platform Specific | Linux | ||
| Permitted Values (Linux) | Type | boolean | |
| Default | FALSE | ||
Some hardware/operating system architectures support memory pages greater than the default (usually 4KB). The actual implementation of this support depends on the underlying hardware and operating system. Applications that perform a lot of memory accesses may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses.
MySQL supports the Linux implementation of large page support
(which is called HugeTLB in Linux). See
Section 8.12.4.2, “Enabling Large Page Support”. For Solaris support of
large pages, see the description of the
--super-large-pages option.
--large-pages is disabled by
default.
| Command-Line Format | --lc-messages=name | ||
| System Variable | Name | lc_messages | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | string | |
| Default | en_US | ||
The locale to use for error messages. The default is
en_US. The server converts the argument to
a language name and combines it with the value of
--lc-messages-dir to produce
the location for the error message file. See
Section 10.2, “Setting the Error Message Language”.
| Command-Line Format | --lc-messages-dir=dir_name | ||
| System Variable | Name | lc_messages_dir | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | directory name | |
The directory where error messages are located. The server
uses the value together with the value of
--lc-messages to produce the
location for the error message file. See
Section 10.2, “Setting the Error Message Language”.
| Command-Line Format | --local-service | ||
(Windows only) A --local-service option
following the service name causes the server to run using the
LocalService Windows account that has
limited system privileges. This account is available only for
Windows XP or newer. If both
--defaults-file and
--local-service are given following the
service name, they can be in any order. See
Section 2.3.7.7, “Starting MySQL as a Windows Service”.
--log[=,
file_name]-l [
file_name]
| Deprecated | 5.1.29, by general-log | ||
| Command-Line Format | --log[=file_name] | ||
| System Variable | Name | log | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | file name | |
This option enables logging to the general query log, which
contains entries that record client connections and SQL
statements received from clients. The log output destination
can be selected with the
--log-output option. If you
omit the file name, MySQL uses
host_name.log
The --log option is deprecated
and is removed (along with the
log system variable) in MySQL
5.6. Instead, use the
--general_log option to enable
the general query log and the
--general_log_file=
option to set the general query log file name.
file_name
| Command-Line Format | --log-error[=file_name] | ||
| System Variable | Name | log_error | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | file name | |
Log errors and startup messages to this file. See
Section 5.4.2, “The Error Log”. If the file name has no
extension, the server adds an extension of
.err. If you omit the file name, the
default log file on Unix and Unix-like systems is
host_name.errhost_name.err--pid-file option is specified.
In that case, the default name is the PID file base name with
a suffix of .err in the data directory.
| Command-Line Format | --log-isam[=file_name] | ||
| Permitted Values | Type | file name | |
Log all MyISAM changes to this file (used
only when debugging MyISAM).
| Deprecated | 4.1.0 | ||
| Command-Line Format | --log-long-format | ||
Log extra information to the binary log and slow query log, if
they have been activated. For example, the user name and
timestamp are logged for all queries. This option is
deprecated, as it now represents the default logging behavior.
(See the description for
--log-short-format.) The
--log-queries-not-using-indexes
option is available for the purpose of logging queries that do
not use indexes to the slow query log.
--log-long-format was removed
in MySQL 5.5.3.
| Command-Line Format | --log-output=name | ||
| System Variable | Name | log_output | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | set | |
| Default | FILE | ||
| Valid Values | TABLE | ||
FILE | |||
NONE | |||
This option determines the destination for general query log
and slow query log output. The option value can be given as
one or more of the words TABLE,
FILE, or NONE.
TABLE select logging to the
general_log and
slow_log tables in the
mysql database as a destination.
FILE selects logging to log files as a
destination. NONE disables logging. If
NONE is present in the option value, it
takes precedence over any other words that are present.
TABLE and FILE can both
be given to select to both log output destinations.
This option selects log output destinations, but does not
enable log output. To do that, use the
--general_log and
--slow_query_log options. For
FILE logging, the
--general_log_file and
-slow_query_log_file options determine the
log file location. For more information, see
Section 5.4.1, “Selecting General Query and Slow Query Log Output Destinations”.
--log-queries-not-using-indexes
| Command-Line Format | --log-queries-not-using-indexes | ||
| System Variable | Name | log_queries_not_using_indexes | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
If you are using this option with the slow query log enabled, queries that are expected to retrieve all rows are logged. See Section 5.4.5, “The Slow Query Log”. This option does not necessarily mean that no index is used. For example, a query that uses a full index scan uses an index but would be logged because the index would not limit the number of rows.
| Command-Line Format | --log-short-format | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
Log less information to the slow query log, if it has been activated.
| Command-Line Format | --log-slow-admin-statements | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
Include slow administrative statements in the statements
written to the slow query log. Administrative statements
include ALTER TABLE,
ANALYZE TABLE,
CHECK TABLE,
CREATE INDEX,
DROP INDEX,
OPTIMIZE TABLE, and
REPAIR TABLE.
--log-slow-queries[=
file_name]
| Deprecated | 5.1.29, by slow-query-log | ||
| Command-Line Format | --log-slow-queries[=name] | ||
| System Variable | Name | log_slow_queries | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
This option enables logging to the slow query log, which
contains entries for all queries that have taken more than
long_query_time seconds to
execute. See the descriptions of the
--log-long-format and
--log-short-format options for
details. The log output destination can be selected with the
--log-output option. If you
omit the file name, MySQL uses
host_name-slow.log
The --log-slow-queries option
is deprecated and is removed (along with the
log_slow_queries system
variable) in MySQL 5.6. Instead, use the
--slow_query_log option to
enable the slow query log and the
--slow_query_log_file=
option to set the slow query log file name.
file_name
| Command-Line Format | --log-tc=file_name | ||
| Permitted Values | Type | file name | |
| Default | tc.log | ||
The name of the memory-mapped transaction coordinator log file
(for XA transactions that affect multiple storage engines when
the binary log is disabled). The default name is
tc.log. The file is created under the
data directory if not given as a full path name. This option
is unused.
| Command-Line Format | --log-tc-size=# | ||
| Permitted Values (32-bit platforms) | Type | integer | |
| Default | 24576 | ||
| Max Value | 4294967295 | ||
| Permitted Values (64-bit platforms, <= 5.5.2) | Type | integer | |
| Default | 24576 | ||
| Max Value | 18446744073709547520 | ||
| Permitted Values (64-bit platforms, >= 5.5.3) | Type | integer | |
| Default | 24576 | ||
| Max Value | 18446744073709551615 | ||
The size in bytes of the memory-mapped transaction coordinator log. The default size is 24KB.
--log-warnings[=,
level]-W [
level]
| Command-Line Format | --log-warnings[=#] | ||
| System Variable | Name | log_warnings | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values (32-bit platforms) | Type | integer | |
| Default | 1 | ||
| Min Value | 0 | ||
| Max Value | 4294967295 | ||
| Permitted Values (64-bit platforms, <= 5.5.2) | Type | integer | |
| Default | 1 | ||
| Min Value | 0 | ||
| Max Value | 18446744073709547520 | ||
| Permitted Values (64-bit platforms, >= 5.5.3) | Type | integer | |
| Default | 1 | ||
| Min Value | 0 | ||
| Max Value | 18446744073709551615 | ||
Print out warnings such as Aborted
connection... to the error log. This option is
enabled (1) by default. To disable it, use
--log-warnings=0. Specifying
the option without a level value
increments the current value by 1. Enabling this option by
setting it greater than 0 is recommended, for example, if you
use replication (you get more information about what is
happening, such as messages about network failures and
reconnections). If the value is greater than 1, aborted
connections are written to the error log, and access-denied
errors for new connection attempts are written. See
Section B.5.2.11, “Communication Errors and Aborted Connections”.
If a slave server was started with
--log-warnings enabled, the
slave prints messages to the error log to provide information
about its status, such as the binary log and relay log
coordinates where it starts its job, when it is switching to
another relay log, when it reconnects after a disconnect, and
so forth. The server logs messages about statements that are
unsafe for statement-based logging if
--log-warnings is greater than
0.
| Command-Line Format | --low-priority-updates | ||
| System Variable | Name | low_priority_updates | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
Give table-modifying operations
(INSERT,
REPLACE,
DELETE,
UPDATE) lower priority than
selects. This can also be done using {INSERT |
REPLACE | DELETE | UPDATE} LOW_PRIORITY ... to lower
the priority of only one query, or by SET
LOW_PRIORITY_UPDATES=1 to change the priority in one
thread. This affects only storage engines that use only
table-level locking (MyISAM,
MEMORY, MERGE). See
Section 8.11.2, “Table Locking Issues”.
--min-examined-row-limit=
number
| Command-Line Format | --min-examined-row-limit=# | ||
| System Variable | Name | min_examined_row_limit | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values (32-bit platforms) | Type | integer | |
| Default | 0 | ||
| Min Value | 0 | ||
| Max Value | 4294967295 | ||
| Permitted Values (64-bit platforms, <= 5.5.2) | Type | integer | |
| Default | 0 | ||
| Min Value | 0 | ||
| Max Value | 18446744073709547520 | ||
| Permitted Values (64-bit platforms, >= 5.5.3) | Type | integer | |
| Default | 0 | ||
| Min Value | 0 | ||
| Max Value | 18446744073709551615 | ||
When this option is set, queries which examine fewer than
number rows are not written to the
slow query log. The default is 0.
| Command-Line Format | --memlock | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
Lock the mysqld process in memory. This option might help if you have a problem where the operating system is causing mysqld to swap to disk.
--memlock works on systems that
support the mlockall() system call; this
includes Solaris, most Linux distributions that use a 2.4 or
higher kernel, and perhaps other Unix systems. On Linux
systems, you can tell whether or not
mlockall() (and thus this option) is
supported by checking to see whether or not it is defined in
the system mman.h file, like this:
shell> grep mlockall /usr/include/sys/mman.h
If mlockall() is supported, you should see
in the output of the previous command something like the
following:
extern int mlockall (int __flags) __THROW;
Use of this option may require you to run the server as
root, which, for reasons of security, is
normally not a good idea. See
Section 6.1.5, “How to Run MySQL as a Normal User”.
On Linux and perhaps other systems, you can avoid the need
to run the server as root by changing the
limits.conf file. See the notes
regarding the memlock limit in
Section 8.12.4.2, “Enabling Large Page Support”.
You must not try to use this option on a system that does
not support the mlockall() system call;
if you do so, mysqld will very likely
crash as soon as you try to start it.
| Command-Line Format | --myisam-block-size=# | ||
| Permitted Values | Type | integer | |
| Default | 1024 | ||
| Min Value | 1024 | ||
| Max Value | 16384 | ||
The block size to be used for MyISAM index
pages.
--myisam-recover[=
option[,option]...]]
This option is renamed as of MySQL 5.5.3 to
--myisam-recover-options. See
the description of that option for more information.
--myisam-recover-options[=
option[,option]...]]
| Introduced | 5.5.3 | ||
| Command-Line Format | --myisam-recover-options[=name] | ||
| Permitted Values | Type | enumeration | |
| Default | OFF | ||
| Valid Values | OFF | ||
DEFAULT | |||
BACKUP | |||
FORCE | |||
QUICK | |||
Set the MyISAM storage engine recovery
mode. The option value is any combination of the values of
OFF, DEFAULT,
BACKUP, FORCE, or
QUICK. If you specify multiple values,
separate them by commas. Specifying the option with no
argument is the same as specifying DEFAULT,
and specifying with an explicit value of ""
disables recovery (same as a value of OFF).
If recovery is enabled, each time mysqld
opens a MyISAM table, it checks whether the
table is marked as crashed or was not closed properly. (The
last option works only if you are running with external
locking disabled.) If this is the case,
mysqld runs a check on the table. If the
table was corrupted, mysqld attempts to
repair it.
The following options affect how the repair works.
| Option | Description |
|---|---|
OFF | No recovery. |
DEFAULT | Recovery without backup, forcing, or quick checking. |
BACKUP | If the data file was changed during recovery, save a backup of the
|
FORCE | Run recovery even if we would lose more than one row from the
.MYD file. |
QUICK | Do not check the rows in the table if there are not any delete blocks. |
Before the server automatically repairs a table, it writes a
note about the repair to the error log. If you want to be able
to recover from most problems without user intervention, you
should use the options BACKUP,FORCE. This
forces a repair of a table even if some rows would be deleted,
but it keeps the old data file as a backup so that you can
later examine what happened.
This option was named
--myisam-recover, before MySQL
5.5.3. The old option name still works because it is
recognized as an unambiguous prefix of the new name,
--myisam-recover-options.
(Option prefix recognition occurs as described in
Section 4.2.3, “Specifying Program Options”.)
The option value OFF is available as of
MySQL 5.5.3.
Do not read any option files. If program startup fails due to
reading unknown options from an option file,
--no-defaults can be used to
prevent them from being read.
| Command-Line Format | --old-alter-table | ||
| System Variable | Name | old_alter_table | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
When this option is given, the server does not use the
optimized method of processing an ALTER
TABLE operation. It reverts to using a temporary
table, copying over the data, and then renaming the temporary
table to the original, as used by MySQL 5.0 and earlier. For
more information on the operation of
ALTER TABLE, see
Section 13.1.7, “ALTER TABLE Syntax”.
| Command-Line Format | --old-style-user-limits | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
Enable old-style user limits. (Before MySQL 5.0.3, account
resource limits were counted separately for each host from
which a user connected rather than per account row in the
user table.) See
Section 6.3.4, “Setting Account Resource Limits”.
| Command-Line Format | --one-thread | ||
Only use one thread (for debugging under Linux). This option is available only if the server is built with debugging enabled. See Section 24.5, “Debugging and Porting MySQL”.
This option is deprecated and is removed in MySQL 5.6. Use
--thread_handling=no-threads
instead.
| Command-Line Format | --open-files-limit=# | ||
| System Variable | Name | open_files_limit | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | integer | |
| Default | 0 | ||
| Min Value | 0 | ||
| Max Value | platform dependent | ||
Changes the number of file descriptors available to
mysqld. You should try increasing the value
of this option if mysqld gives you the
error Too many open files.
mysqld uses the option value to reserve
descriptors with setrlimit(). Internally,
the maximum value for this option is the maximum unsigned
integer value, but the actual maximum is platform dependent.
If the requested number of file descriptors cannot be
allocated, mysqld writes a warning to the
error log.
mysqld may attempt to allocate more than
the requested number of descriptors (if they are available),
using the values of
max_connections and
table_open_cache to estimate
whether more descriptors will be needed.
On Unix, the value cannot be set less than ulimit -n.
| Command-Line Format | --partition | ||
| Disabled by | skip-partition | ||
| Permitted Values | Type | boolean | |
| Default | ON | ||
Enables or disables user-defined partitioning support in the MySQL Server.
| Command-Line Format | --pid-file=file_name | ||
| System Variable | Name | pid_file | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | file name | |
The path name of the process ID file. The server creates the file in the data directory unless an absolute path name is given to specify a different directory. This file is used by other programs such as mysqld_safe to determine the server's process ID.
Specifies an option that pertains to a server plugin. For
example, many storage engines can be built as plugins, and for
such engines, options for them can be specified with a
--plugin prefix. Thus, the
--innodb_file_per_table option
for InnoDB can be specified as
--plugin-innodb_file_per_table.
For boolean options that can be enabled or disabled, the
--skip prefix and other alternative formats
are supported as well (see
Section 4.2.5, “Program Option Modifiers”). For example,
--skip-plugin-innodb_file_per_table
disables innodb_file_per_table.
The rationale for the --plugin prefix is that
it enables plugin options to be specified unambiguously if
there is a name conflict with a built-in server option. For
example, were a plugin writer to name a plugin
“sql” and implement a “mode” option,
the option name might be
--sql-mode, which would
conflict with the built-in option of the same name. In such
cases, references to the conflicting name are resolved in
favor of the built-in option. To avoid the ambiguity, users
can specify the plugin option as
--plugin-sql-mode. Use of the
--plugin prefix for plugin options is
recommended to avoid any question of ambiguity.
| Command-Line Format | --plugin-load=plugin_list | ||
| Permitted Values | Type | string | |
This option tells the server to load the named plugins at
startup. All plugins to load must be named in the same
--plugin-load option. If
multiple --plugin-load options
are given, only the last one is used.
The option value is a semicolon-separated list of
name=plugin_library
and plugin_library values. Each
name is the name of a plugin to
load, and plugin_library is the
name of the library file that contains the plugin code. If a
plugin library is named without any preceding plugin name, the
server loads all plugins in the library. The server looks for
plugin library files in the directory named by the
plugin_dir system variable.
For example, if plugins named myplug1 and
myplug2 have library files
myplug1.so and
myplug2.so, use this option to perform an
early plugin load:
shell> mysqld --plugin-load="myplug1=myplug1.so;myplug2=myplug2.so"
Quotes are used around the argument value here because
otherwise semicolon (;) is interpreted as a
special character by some command interpreters. (Unix shells
treat it as a command terminator, for example.)
Each named plugin is loaded for a single invocation of
mysqld only. After a restart, the plugin is
not loaded unless --plugin-load
is used again. This is in contrast to
INSTALL PLUGIN, which adds an
entry to the mysql.plugins table to cause
the plugin to be loaded for every normal server startup.
Under normal startup, the server determines which plugins to
load by reading the mysql.plugins system
table. If the server is started with the
--skip-grant-tables option, it
does not consult the mysql.plugins table
and does not load plugins listed there.
--plugin-load enables plugins
to be loaded even when
--skip-grant-tables is given.
--plugin-load also enables
plugins to be loaded at startup under configurations when
plugins cannot be loaded at runtime.
For additional information about plugin loading, see Section 5.5.2, “Installing and Uninstalling Plugins”.
--port=,
port_num-P
port_num
| Command-Line Format | --port=# | ||
| System Variable | Name | port | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | integer | |
| Default | 3306 | ||
| Min Value | 0 | ||
| Max Value | 65535 | ||
The port number to use when listening for TCP/IP connections.
On Unix and Unix-like systems, the port number must be 1024 or
higher unless the server is started by the
root system user.
| Command-Line Format | --port-open-timeout=# | ||
| Permitted Values | Type | integer | |
| Default | 0 | ||
On some systems, when the server is stopped, the TCP/IP port might not become available immediately. If the server is restarted quickly afterward, its attempt to reopen the port can fail. This option indicates how many seconds the server should wait for the TCP/IP port to become free if it cannot be opened. The default is not to wait.
Print the program name and all options that it gets from option files.
| Command-Line Format | --remove [service_name] | ||
| Platform Specific | Windows | ||
(Windows only) Remove a MySQL Windows service. The default
service name is MySQL if no
service_name value is given. For
more information, see Section 2.3.7.7, “Starting MySQL as a Windows Service”.
| Deprecated | 5.5.26 | ||
| Command-Line Format | --safe-mode | ||
Skip some optimization stages. This option is deprecated and is removed in MySQL 5.6.
| Deprecated | 4.0.2 | ||
| Removed | 5.5.3 | ||
| Command-Line Format | --safe-show-database | ||
| Permitted Values | Type | boolean | |
This option is deprecated and does not do anything because
there is a SHOW DATABASES
privilege that can be used to control access to database names
on a per-account basis. See
Section 6.2.1, “Privileges Provided by MySQL”.
--safe-show-database was
removed in MySQL 5.5.3.
| Command-Line Format | --safe-user-create | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
If this option is enabled, a user cannot create new MySQL
users by using the GRANT
statement unless the user has the
INSERT privilege for the
mysql.user table or any column in the
table. If you want a user to have the ability to create new
users that have those privileges that the user has the right
to grant, you should grant the user the following privilege:
GRANT INSERT(user) ON mysql.user TO 'user_name'@'host_name';
This ensures that the user cannot change any privilege columns
directly, but has to use the
GRANT statement to give
privileges to other users.
| Command-Line Format | --secure-auth | ||
| System Variable | Name | secure_auth | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
This option causes the server to block connections by clients that attempt to use accounts that have passwords stored in the old (pre-4.1) format. Use it to prevent all use of passwords employing the old format (and hence insecure communication over the network).
Server startup fails with an error if this option is enabled and the privilege tables are in pre-4.1 format. See Section B.5.2.4, “Client does not support authentication protocol”.
The mysql client also has a
--secure-auth option, which
prevents connections to a server if the server requires a
password in old format for the client account.
Passwords that use the pre-4.1 hashing method are less secure than passwords that use the native password hashing method and should be avoided.
| Command-Line Format | --secure-file-priv=dir_name | ||
| System Variable | Name | secure_file_priv | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values (<= 5.5.52) | Type | string | |
| Default | empty | ||
| Valid Values | empty | ||
dirname | |||
| Permitted Values (>= 5.5.53) | Type | string | |
| Default | platform specific | ||
| Valid Values | empty | ||
dirname | |||
NULL | |||
This option sets the
secure_file_priv system
variable, which is used to limit the effect of data import and
export operations, such as those performed by the
LOAD DATA and
SELECT ... INTO
OUTFILE statements and the
LOAD_FILE() function. For more
information, see the description of
secure_file_priv.
| Command-Line Format | --shared_memory[={0,1}] | ||
| System Variable | Name | shared_memory | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Platform Specific | Windows | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
Enable shared-memory connections by local clients. This option is available only on Windows.
--shared-memory-base-name=
name
| Command-Line Format | --shared_memory_base_name=name | ||
| System Variable | Name | shared_memory_base_name | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Platform Specific | Windows | ||
| Permitted Values | Type | string | |
| Default | MYSQL | ||
The name of shared memory to use for shared-memory
connections. This option is available only on Windows. The
default name is MYSQL. The name is case
sensitive.
Turn off the ability to select and insert at the same time on
MyISAM tables. (This is to be used only if
you think you have found a bug in this feature.) See
Section 8.11.3, “Concurrent Inserts”.
| Command-Line Format | --skip-event-scheduler | ||
--disable-event-scheduler | |||
Turns the Event Scheduler OFF. This is not
the same as disabling the Event Scheduler, which requires
setting
--event-scheduler=DISABLED; see
The
--event-scheduler Option, for more
information.
This option causes the server to start without using the
privilege system at all, which gives anyone with access to the
server unrestricted access to all
databases. You can cause a running server to start
using the grant tables again by executing mysqladmin
flush-privileges or mysqladmin
reload command from a system shell, or by issuing a
MySQL FLUSH
PRIVILEGES statement after connecting to the server.
This option also causes the server to suppress during its
startup sequence the loading of user-defined functions (UDFs),
scheduled events, and plugins that were installed with the
INSTALL PLUGIN statement. To
cause plugins to be loaded anyway, use the
--plugin-load option.
FLUSH
PRIVILEGES might be executed implicitly by other
actions performed after startup. For example,
mysql_upgrade flushes the privileges during
the upgrade procedure.
Disable use of the internal host cache for faster name-to-IP resolution. In this case, the server performs a DNS lookup every time a client connects. See Section 8.12.5.2, “DNS Lookup Optimization and the Host Cache”.
Disable the InnoDB storage engine. In this
case, if the default storage engine is
InnoDB, the server will not start
unless you also use
--default-storage-engine to set
the default to some other engine.
Do not resolve host names when checking client connections.
Use only IP addresses. If you use this option, all
Host column values in the grant tables must
be IP addresses or localhost. See
Section 8.12.5.2, “DNS Lookup Optimization and the Host Cache”.
Depending on the network configuration of your system and the
Host values for your accounts, clients may
need to connect using an explicit --host
option, such as --host=localhost,
--host=127.0.0.1, or
--host=::1.
An attempt to connect to the host 127.0.0.1
normally resolves to the localhost account.
However, this fails if the server is run with the
--skip-name-resolve option, so
make sure that an account exists that can accept a connection.
For example, to be able to connect as root
using --host=127.0.0.1 or
--host=::1, create these accounts:
CREATE USER 'root'@'127.0.0.1' IDENTIFIED BY 'root-password'; CREATE USER 'root'@'::1' IDENTIFIED BY 'root-password';
Do not listen for TCP/IP connections at all. All interaction with mysqld must be made using named pipes or shared memory (on Windows) or Unix socket files (on Unix). This option is highly recommended for systems where only local clients are permitted. See Section 8.12.5.2, “DNS Lookup Optimization and the Host Cache”.
| Command-Line Format | --skip-partition | ||
--disable-partition | |||
Disables user-defined partitioning. Partitioned tables can be
seen using SHOW TABLES or by
querying the
INFORMATION_SCHEMA.TABLES table,
but cannot be created or modified, nor can data in such tables
be accessed. All partition-specific columns in the
INFORMATION_SCHEMA.PARTITIONS
table display NULL.
Since DROP TABLE removes table
definition (.frm) files, this statement
works on partitioned tables even when partitioning is disabled
using the option. The statement, however, does not remove
.par files associated with partitioned
tables in such cases. For this reason, you should avoid
dropping partitioned tables with partitioning disabled, or
take action to remove the orphaned .par
files manually.
Options that begin with --ssl
specify whether to permit clients to connect using SSL and
indicate where to find SSL keys and certificates. See
Section 6.4.5, “Command Options for Secure Connections”.
| Command-Line Format | --standalone | ||
| Platform Specific | Windows | ||
Available on Windows only; instructs the MySQL server not to run as a service.
| Introduced | 5.5.3 | ||
| Command-Line Format | --super-large-pages | ||
| Platform Specific | Solaris | ||
| Permitted Values (Solaris) | Type | boolean | |
| Default | FALSE | ||
Standard use of large pages in MySQL attempts to use the
largest size supported, up to 4MB. Under Solaris, a
“super large pages” feature enables uses of pages
up to 256MB. This feature is available for recent SPARC
platforms. It can be enabled or disabled by using the
--super-large-pages or
--skip-super-large-pages
option.
--symbolic-links,
--skip-symbolic-links
| Command-Line Format | --symbolic-links | ||
Enable or disable symbolic link support. This option has different effects on Windows and Unix:
On Windows, enabling symbolic links enables you to
establish a symbolic link to a database directory by
creating a
db_name.sym
On Unix, enabling symbolic links means that you can link a
MyISAM index file or data file to
another directory with the INDEX
DIRECTORY or DATA DIRECTORY
options of the CREATE TABLE
statement. If you delete or rename the table, the files
that its symbolic links point to also are deleted or
renamed. See Section 8.12.3.2, “Using Symbolic Links for MyISAM Tables on Unix”.
| Removed | 5.5.6 | ||
| Command-Line Format | --skip-safemalloc | ||
Previously, if MySQL was configured with full debugging
support, all MySQL programs check for memory overruns during
each memory allocation and memory freeing operation. This
checking is very slow, so for the server you can avoid it when
you do not need it by using the
--skip-safemalloc option.
safemalloc, along with this option, was
removed in MySQL 5.5.6.
| Command-Line Format | --skip-show-database | ||
| System Variable | Name | skip_show_database | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
This option sets the
skip_show_database system
variable that controls who is permitted to use the
SHOW DATABASES statement. See
Section 5.1.5, “Server System Variables”.
| Command-Line Format | --skip-stack-trace | ||
Do not write stack traces. This option is useful when you are running mysqld under a debugger. On some systems, you also must use this option to get a core file. See Section 24.5, “Debugging and Porting MySQL”.
| Deprecated | 5.1.29 | ||
| Command-Line Format | --skip-thread-priority | ||
Disable using thread priorities for faster response time. This option is deprecated and is removed in MySQL 5.6.
| Command-Line Format | --slow-query-log | ||
| System Variable | Name | slow_query_log | |
| Variable Scope | Global | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | boolean | |
| Default | OFF | ||
Specify the initial slow query log state. With no argument or
an argument of 1, the
--slow-query-log option enables
the log. If omitted or given with an argument of 0, the option
disables the log.
| Introduced | 5.5.20 | ||
| Command-Line Format | --slow-start-timeout=# | ||
| Permitted Values (Windows) | Type | integer | |
| Default | 15000 | ||
This option controls the Windows service control manager's service start timeout. The value is the maximum number of milliseconds that the service control manager waits before trying to kill the windows service during startup. The default value is 15000 (15 seconds). If the MySQL service takes too long to start, you may need to increase this value. A value of 0 means there is no timeout.
| Command-Line Format | --socket={file_name|pipe_name} | ||
| System Variable | Name | socket | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | string | |
| Default | /tmp/mysql.sock | ||
On Unix, this option specifies the Unix socket file to use
when listening for local connections. The default value is
/tmp/mysql.sock. If this option is given,
the server creates the file in the data directory unless an
absolute path name is given to specify a different directory.
On Windows, the option specifies the pipe name to use when
listening for local connections that use a named pipe. The
default value is MySQL (not case
sensitive).
--sql-mode=
value[,value[,value...]]
| Command-Line Format | --sql-mode=name | ||
| System Variable | Name | sql_mode | |
| Variable Scope | Global, Session | ||
| Dynamic Variable | Yes | ||
| Permitted Values | Type | set | |
| Default | '' | ||
| Valid Values | ALLOW_INVALID_DATES | ||
ANSI_QUOTES | |||
ERROR_FOR_DIVISION_BY_ZERO | |||
HIGH_NOT_PRECEDENCE | |||
IGNORE_SPACE | |||
NO_AUTO_CREATE_USER | |||
NO_AUTO_VALUE_ON_ZERO | |||
NO_BACKSLASH_ESCAPES | |||
NO_DIR_IN_CREATE | |||
NO_ENGINE_SUBSTITUTION | |||
NO_FIELD_OPTIONS | |||
NO_KEY_OPTIONS | |||
NO_TABLE_OPTIONS | |||
NO_UNSIGNED_SUBTRACTION | |||
NO_ZERO_DATE | |||
NO_ZERO_IN_DATE | |||
ONLY_FULL_GROUP_BY | |||
PAD_CHAR_TO_FULL_LENGTH | |||
PIPES_AS_CONCAT | |||
REAL_AS_FLOAT | |||
STRICT_ALL_TABLES | |||
STRICT_TRANS_TABLES | |||
Set the SQL mode. See Section 5.1.8, “Server SQL Modes”.
MySQL installation programs may configure the SQL mode during the installation process. If the SQL mode differs from the default or from what you expect, check for a setting in an option file that the server reads at startup.
| Command-Line Format | --sysdate-is-now | ||
| Permitted Values | Type | boolean | |
| Default | FALSE | ||
SYSDATE() by default returns
the time at which it executes, not the time at which the
statement in which it occurs begins executing. This differs
from the behavior of NOW().
This option causes SYSDATE() to
be an alias for NOW(). For
information about the implications for binary logging and
replication, see the description for
SYSDATE() in
Section 12.7, “Date and Time Functions” and for SET
TIMESTAMP in
Section 5.1.5, “Server System Variables”.
--tc-heuristic-recover={COMMIT|ROLLBACK}
| Command-Line Format | --tc-heuristic-recover=name | ||
| Permitted Values | Type | enumeration | |
| Default | COMMIT | ||
| Valid Values | COMMIT | ||
ROLLBACK | |||
The type of decision to use in the heuristic recovery process. To use this option, two or more storage engines that support XA transactions must be installed.
| Command-Line Format | --temp-pool | ||
| Permitted Values | Type | boolean | |
| Default | TRUE | ||
This option causes most temporary files created by the server to use a small set of names, rather than a unique name for each new file. This works around a problem in the Linux kernel dealing with creating many new files with different names. With the old behavior, Linux seems to “leak” memory, because it is being allocated to the directory entry cache rather than to the disk cache. This option is ignored except on Linux.
| Command-Line Format | --transaction-isolation=name | ||
| Permitted Values | Type | enumeration | |
| Default | REPEATABLE-READ | ||
| Valid Values | READ-UNCOMMITTED | ||
READ-COMMITTED | |||
REPEATABLE-READ | |||
SERIALIZABLE | |||
Sets the default transaction isolation level. The
level value can be
READ-UNCOMMITTED,
READ-COMMITTED,
REPEATABLE-READ, or
SERIALIZABLE. See
Section 13.3.6, “SET TRANSACTION Syntax”.
The default transaction isolation level can also be set at
runtime using the SET
TRANSACTION statement or by setting the
tx_isolation system variable.
--tmpdir=,
dir_name-t
dir_name
| Command-Line Format | --tmpdir=dir_name | ||
| System Variable | Name | tmpdir | |
| Variable Scope | Global | ||
| Dynamic Variable | No | ||
| Permitted Values | Type | directory name | |
The path of the directory to use for creating temporary files.
It might be useful if your default /tmp
directory resides on a partition that is too small to hold
temporary tables. This option accepts several paths that are
used in round-robin fashion. Paths should be separated by
colon characters (:) on Unix and semicolon
characters (;) on Windows. If the MySQL
server is acting as a replication slave, you should not set
--tmpdir to point to a
directory on a memory-based file system or to a directory that
is cleared when the server host restarts. For more information
about the storage location of temporary files, see
Section B.5.3.5, “Where MySQL Stores Temporary Files”. A replication slave needs
some of its temporary files to survive a machine restart so
that it can replicate temporary tables or
LOAD DATA
INFILE operations. If files in the temporary file
directory are lost when the server restarts, replication
fails.
--user={,
user_name|user_id}-u
{
user_name|user_id}
| Command-Line Format | --user=name | ||
| Permitted Values | Type | string | |
Run the mysqld server as the user having
the name user_name or the numeric
user ID user_id.
(“User” in this context refers to a system login
account, not a MySQL user listed in the grant tables.)
This option is mandatory when starting
mysqld as root. The
server changes its user ID during its startup sequence,
causing it to run as that particular user rather than as
root. See
Section 6.1.1, “Security Guidelines”.
To avoid a possible security hole where a user adds a
--user=root option to a
my.cnf file (thus causing the server to
run as root), mysqld
uses only the first --user
option specified and produces a warning if there are multiple
--user options. Options in
/etc/my.cnf and
$MYSQL_HOME/my.cnf are processed before
command-line options, so it is recommended that you put a
--user option in
/etc/my.cnf and specify a value other
than root. The option in
/etc/my.cnf is found before any other
--user options, which ensures
that the server runs as a user other than
root, and that a warning results if any
other --user option is found.
Use this option with the --help
option for detailed help.
--version, -V
Display version information and exit.