--ndb-batch-size=#

This sets the size in bytes that is used for NDB transaction batches.

--ndb-cluster-connection-pool=#

By setting this option to a value greater than 1 (the default), a mysqld process can use multiple connections to the cluster, effectively mimicking several SQL nodes. Each connection requires its own [api] or [mysqld] section in the cluster configuration (config.ini) file, and counts against the maximum number of API connections supported by the cluster.

Suppose that you have 2 cluster host computers, each running an SQL node whose mysqld process was started with --ndb-cluster-connection-pool=4; this means that the cluster must have 8 API slots available for these connections (instead of 2). All of these connections are set up when the SQL node connects to the cluster, and are allocated to threads in a round-robin fashion.

This option is useful only when running mysqld on host machines having multiple CPUs, multiple cores, or both. For best results, the value should be smaller than the total number of cores available on the host machine. Setting it to a value greater than this is likely to degrade performance severely.

--ndb-blob-read-batch-bytes=bytes

This option can be used to set the size (in bytes) for batching of BLOB data reads in NDB Cluster applications. When this batch size is exceeded by the amount of BLOB data to be read within the current transaction, any pending BLOB read operations are immediately executed.

The maximum value for this option is 4294967295; the default is 65536. Setting it to 0 has the effect of disabling BLOB read batching.

--ndb-blob-write-batch-bytes=bytes

This option can be used to set the size (in bytes) for batching of BLOB data writes in NDB Cluster applications. When this batch size is exceeded by the amount of BLOB data to be written within the current transaction, any pending BLOB write operations are immediately executed.

The maximum value for this option is 4294967295; the default is 65536. Setting it to 0 has the effect of disabling BLOB write batching.

--ndb-connectstring=connection_string

When using the NDBCLUSTER storage engine, this option specifies the management server that distributes cluster configuration data. See Section 18.3.3.3, “NDB Cluster Connection Strings”, for syntax.

--ndb-deferred-constraints=[0|1]

Controls whether or not constraint checks on unique indexes are deferred until commit time, where such checks are supported. 0 is the default.

This option is not normally needed for operation of NDB Cluster or NDB Cluster Replication, and is intended primarily for use in testing.

--ndb-distribution=[KEYHASH|LINHASH]

Controls the default distribution method for NDB tables. Can be set to either of KEYHASH (key hashing) or LINHASH (linear hashing). KEYHASH is the default.

--ndb-mgmd-host=host[:port]

Can be used to set the host and port number of a single management server for the program to connect to. If the program requires node IDs or references to multiple management servers (or both) in its connection information, use the --ndb-connectstring option instead.

--ndbcluster

The NDBCLUSTER storage engine is necessary for using NDB Cluster. If a mysqld binary includes support for the NDBCLUSTER storage engine, the engine is disabled by default. Use the --ndbcluster option to enable it. Use --skip-ndbcluster to explicitly disable the engine.

--ndb-log-apply-status

Causes a slave mysqld to log any updates received from its immediate master to the mysql.ndb_apply_status table in its own binary log using its own server ID rather than the server ID of the master. In a circular or chain replication setting, this allows such updates to propagate to the mysql.ndb_apply_status tables of any MySQL servers configured as slaves of the current mysqld.

In a chain replication setup, using this option allows downstream (slave) clusters to be aware of their positions relative to all of their upstream contributors (masters).

In a circular replication setup, this option causes changes to ndb_apply_status tables to complete the entire circuit, eventually propagating back to the originating NDB Cluster. This also allows a cluster acting as a master to see when its changes (epochs) have been applied to the other clusters in the circle.

This option has no effect unless the MySQL server is started with the --ndbcluster option.

--ndb-log-empty-epochs=[ON|OFF]

Causes epochs during which there were no changes to be written to the ndb_apply_status and ndb_binlog_index tables, even when --log-slave-updates is enabled.

By default this option is disabled. Disabling --ndb-log-empty-epochs causes epoch transactions with no changes not to be written to the binary log, although a row is still written even for an empty epoch in ndb_binlog_index.

Because --ndb-log-empty-epochs=1 causes the size of the ndb_binlog_index table to increase independently of the size of the binary log, users should be prepared to manage the growth of this table, even if they expect the cluster to be idle a large part of the time.

--ndb-log-empty-update=[ON|OFF]

Causes updates that produced no changes to be written to the ndb_apply_status and ndb_binlog_index tables, even when --log-slave-updates is enabled.

By default this option is disabled (OFF). Disabling --ndb-log-empty-update causes updates with no changes not to be written to the binary log.

--ndb-log-orig

Log the originating server ID and epoch in the ndb_binlog_index table.

Note that this makes it possible for a given epoch to have multiple rows in ndb_binlog_index, one for each originating epoch.

For more information, see Section 18.6.4, “NDB Cluster Replication Schema and Tables”.

--ndb-log-transaction-id

Causes a slave mysqld to write the NDB transaction ID in each row of the binary log. Such logging requires the use of the Version 2 event format for the binary log; thus, --log-bin-use-v1-row-events must be set to FALSE in order to use this option.

This option is available beginning with NDB 7.2.1 (and is not supported in mainline MySQL Server 5.5). It is required to enable NDB Cluster Replication conflict detection and resolution using the NDB$EPOCH_TRANS() function introduced in the same NDB Cluster release.

The default value is FALSE.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

--ndb-nodeid=#

Set this MySQL server's node ID in an NDB Cluster.

The --ndb-nodeid option overrides any node ID set with --ndb-connectstring, regardless of the order in which the two options are used.

In addition, if --ndb-nodeid is used, then either a matching node ID must be found in a [mysqld] or [api] section of config.ini, or there must be an “open” [mysqld] or [api] section in the file (that is, a section without a NodeId or Id parameter specified). This is also true if the node ID is specified as part of the connection string.

Regardless of how the node ID is determined, its is shown as the value of the global status variable Ndb_cluster_node_id in the output of SHOW STATUS, and as cluster_node_id in the connection row of the output of SHOW ENGINE NDBCLUSTER STATUS.

For more information about node IDs for NDB Cluster SQL nodes, see Section 18.3.3.7, “Defining SQL and Other API Nodes in an NDB Cluster”.

--ndb_optimization_delay=milliseconds

Set the number of milliseconds to wait between sets of rows by OPTIMIZE TABLE statements on NDB tables. The default is 10.

ndb-transid-mysql-connection-map=state

Enables or disables the plugin that handles the ndb_transid_mysql_connection_map table in the INFORMATION_SCHEMA database. Takes one of the values ON, OFF, or FORCE. ON (the default) enables the plugin. OFF disables the plugin, which makes ndb_transid_mysql_connection_map inaccessible. FORCE keeps the MySQL Server from starting if the plugin fails to load and start.

You can see whether the ndb_transid_mysql_connection_map table plugin is running by checking the output of SHOW PLUGINS.

This option was added in NDB 7.2.2.

--ndb-wait-connected=seconds

This option sets the period of time that the MySQL server waits for connections to NDB Cluster management and data nodes to be established before accepting MySQL client connections. The time is specified in seconds. The default value is 30.

--ndb-wait-setup=seconds

This variable shows the period of time that the MySQL server waits for the NDB storage engine to complete setup before timing out and treating NDB as unavailable. The time is specified in seconds. The default value is 30.

--server-id-bits=#

This option indicates the number of least significant bits within the 32-bit server_id which actually identify the server. Indicating that the server is actually identified by fewer than 32 bits makes it possible for some of the remaining bits to be used for other purposes, such as storing user data generated by applications using the NDB API's Event API within the AnyValue of an OperationOptions structure (NDB Cluster uses the AnyValue to store the server ID).

When extracting the effective server ID from server_id for purposes such as detection of replication loops, the server ignores the remaining bits. The --server-id-bits option is used to mask out any irrelevant bits of server_id in the IO and SQL threads when deciding whether an event should be ignored based on the server ID.

This data can be read from the binary log by mysqlbinlog, provided that it is run with its own --server-id-bits option set to 32 (the default).

The value of server_id must be less than 2 ^ server_id_bits; otherwise, mysqld refuses to start.

This system variable is supported only by NDB Cluster. It is not supported in the standard MySQL 5.5 Server.

--skip-ndbcluster

Disable the NDBCLUSTER storage engine. This is the default for binaries that were built with NDBCLUSTER storage engine support; the server allocates memory and other resources for this storage engine only if the --ndbcluster option is given explicitly. See Section 18.3.1, “Quick Test Setup of NDB Cluster”, for an example.

have_ndbcluster

YES if mysqld supports NDBCLUSTER tables. DISABLED if --skip-ndbcluster is used.

This variable is deprecated and is removed in MySQL 5.6. Use SHOW ENGINES instead.

ndb_autoincrement_prefetch_sz

Determines the probability of gaps in an autoincremented column. Set it to 1 to minimize this. Setting it to a high value for optimization makes inserts faster, but decreases the likelihood that consecutive autoincrement numbers will be used in a batch of inserts. The mininum and default value is 1. The maximum value for ndb_autoincrement_prefetch_sz is 65536.

This variable affects only the number of AUTO_INCREMENT IDs that are fetched between statements; within a given statement, at least 32 IDs are obtained at a time. The default value is 1.

ndb_cache_check_time

The number of milliseconds that elapse between checks of NDB Cluster SQL nodes by the MySQL query cache. Setting this to 0 (the default and minimum value) means that the query cache checks for validation on every query.

The recommended maximum value for this variable is 1000, which means that the check is performed once per second. A larger value means that the check is performed and possibly invalidated due to updates on different SQL nodes less often. It is generally not desirable to set this to a value greater than 2000.

ndb_deferred_constraints

Controls whether or not constraint checks are deferred, where these are supported. 0 is the default.

This variable is not normally needed for operation of NDB Cluster or NDB Cluster Replication, and is intended primarily for use in testing.

ndb_distribution

Controls the default distribution method for NDB tables. Can be set to either of KEYHASH (key hashing) or LINHASH (linear hashing). KEYHASH is the default.

ndb_eventbuffer_max_alloc

Sets the maximum amount memory (in bytes) that can be allocated for buffering events by the NDB API. 0 means that no limit is imposed, and is the default.

This variable was added in NDB 7.2.14.

ndb_extra_logging

This variable enables recording in the MySQL error log of information specific to the NDB storage engine.

When this variable is set to 0, the only information specific to NDB that is written to the MySQL error log relates to transaction handling. If it set to a value greater than 0 but less than 10, NDB table schema and connection events are also logged, as well as whether or not conflict resolution is in use, and other NDB errors and information. If the value is set to 10 or more, information about NDB internals, such as the progress of data distribution among cluster nodes, is also written to the MySQL error log. The default is 1.

ndb_force_send

Forces sending of buffers to NDB immediately, without waiting for other threads. Defaults to ON.

ndb_index_stat_cache_entries

Sets the granularity of the statistics by determining the number of starting and ending keys to store in the statistics memory cache. Zero means no caching takes place; in this case, the data nodes are always queried directly. Default value: 32.

This variable was deprecated in MySQL 5.1, and is removed from NDB 7.2.16 and later.

ndb_index_stat_enable

Use NDB index statistics in query optimization. ON is the default in NDB Cluster 7.2 and later.

ndb_index_stat_option

This variable is used for providing tuning options for NDB index statistics generation. The list consist of comma-separated name-value pairs of option names and values. Note that this list must not contain any space characters.

Options not used when setting ndb_index_stat_option are not changed from their default values. For example, you can set ndb_index_stat_option = 'loop_idle=1000ms,cache_limit=32M'.

Time values can be optionally suffixed with h (hours), m (minutes), or s (seconds). Millisecond values can optionally be specified using ms; millisecond values cannot be specified using h, m, or s.) Integer values can be suffixed with K, M, or G.

The names of the options that can be set using this variable are shown in the table that follows. The table also provides brief descriptions of the options, their default values, and (where applicable) their minimum and maximum values.

ndb_index_stat_option was added in NDB 7.2.1.

ndb_index_stat_update_freq

How often to query data nodes instead of the statistics cache. For example, a value of 20 (the default) means to direct every 20^th query to the data nodes.

This variable was deprecated in MySQL 5.1, and is removed from NDB 7.2.16 and later.

ndb_join_pushdown

Added in NDB 7.2.0, this variable controls whether joins on NDB tables are pushed down to the NDB kernel (data nodes). Previously, a join was handled using multiple accesses of NDB by the SQL node; however, when ndb_join_pushdown is enabled, a pushable join is sent in its entirety to the data nodes, where it can be distributed among the data nodes and executed in parallel on multiple copies of the data, with a single, merged result being returned to mysqld. This can reduce greatly the number of round trips between an SQL node and the data nodes required to handle such a join.

By default, ndb_join_pushdown is enabled.

Conditions for NDB pushdown joins.  In order for a join to be pushable, it must meet the following conditions:

You can see whether a given join can be pushed down by checking it with EXPLAIN; when the join can be pushed down, you can see references to the pushed join in the Extra column of the output, as shown in this example:

mysql> EXPLAIN
    ->     SELECT e.first_name, e.last_name, t.title, d.dept_name
    ->         FROM employees e
    ->         JOIN dept_emp de ON e.emp_no=de.emp_no
    ->         JOIN departments d ON d.dept_no=de.dept_no
    ->         JOIN titles t ON e.emp_no=t.emp_no\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: d
         type: ALL
possible_keys: PRIMARY
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 9
        Extra: Parent of 4 pushed join@1
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: de
         type: ref
possible_keys: PRIMARY,emp_no,dept_no
          key: dept_no
      key_len: 4
          ref: employees.d.dept_no
         rows: 5305
        Extra: Child of 'd' in pushed join@1
*************************** 3. row ***************************
           id: 1
  select_type: SIMPLE
        table: e
         type: eq_ref
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 4
          ref: employees.de.emp_no
         rows: 1
        Extra: Child of 'de' in pushed join@1
*************************** 4. row ***************************
           id: 1
  select_type: SIMPLE
        table: t
         type: ref
possible_keys: PRIMARY,emp_no
          key: emp_no
      key_len: 4
          ref: employees.de.emp_no
         rows: 19
        Extra: Child of 'e' in pushed join@1
4 rows in set (0.00 sec)

Two additional sources of information about pushed join performance are available:

ndb_log_apply_status

A read-only variable which shows whether the server was started with the --ndb-log-apply-status option.

ndb_log_bin

Causes updates to NDB tables to be written to the binary log. Setting this variable has no effect if binary logging is not already enabled for the server using log_bin. ndb_log_bin defaults to 1 (ON); normally, there is never any need to change this value in a production environment.

ndb_log_binlog_index

Causes a mapping of epochs to positions in the binary log to be inserted into the ndb_binlog_index table. Setting this variable has no effect if binary logging is not already enabled for the server using log_bin. (In addition, ndb_log_bin must not be disabled.) ndb_log_binlog_index defaults to 1 (ON); normally, there is never any need to change this value in a production environment.

ndb_log_empty_epochs

When this variable is set to 0, epoch transactions with no changes are not written to the binary log, although a row is still written even for an empty epoch in ndb_binlog_index.

ndb_log_empty_update

When this variable is set to ON (1), update transactions with no changes are written to the binary log, even when --log-slave-updates is enabled.

ndb_log_orig

Shows whether the originating server ID and epoch are logged in the ndb_binlog_index table. Set using the --ndb-log-orig server option.

ndb_log_transaction_id

This read-only, Boolean system variable shows whether a slave mysqld writes NDB transaction IDs in the binary log (required to use “active-active” NDB Cluster Replication with NDB$EPOCH_TRANS() conflict detection). To change the setting, use the --ndb-log-transaction-id option.

ndb_log_transaction_id is available in NDB 7.2.1 and later. It is not supported in mainline MySQL Server 5.5.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

ndb_optimized_node_selection

There are two forms of optimized node selection, described here:

This option takes one of the integer values 0, 1, 2, or 3. 3 is the default. These values affect node selection as follows:

Proximity is determined as follows:

ndb_report_thresh_binlog_epoch_slip

This is a threshold on the number of epochs to be behind before reporting binary log status. For example, a value of 3 (the default) means that if the difference between which epoch has been received from the storage nodes and which epoch has been applied to the binary log is 3 or more, a status message is sent to the cluster log.

ndb_report_thresh_binlog_mem_usage

This is a threshold on the percentage of free memory remaining before reporting binary log status. For example, a value of 10 (the default) means that if the amount of available memory for receiving binary log data from the data nodes falls below 10%, a status message is sent to the cluster log.

slave_allow_batching

Whether or not batched updates are enabled on NDB Cluster replication slaves.

This variable is available for mysqld only as supplied with NDB Cluster or built from the NDB Cluster sources. For more information, see Section 18.6.6, “Starting NDB Cluster Replication (Single Replication Channel)”.

Setting this variable had no effect in NDB Cluster 7.2 prior to NDB 7.2.10. (Bug #15953730)

ndb_table_no_logging

When this variable is set to ON or 1, it causes NDB tables not to be checkpointed to disk. More specifically, this setting applies to tables which are created or altered using ENGINE NDB when ndb_table_no_logging is enabled, and continues to apply for the lifetime of the table, even if ndb_table_no_logging is later changed. Suppose that A, B, C, and D are tables that we create (and perhaps also alter), and that we also change the setting for ndb_table_no_logging as shown here:

SET @@ndb_table_no_logging = 1;

CREATE TABLE A ... ENGINE NDB;

CREATE TABLE B ... ENGINE MYISAM;
CREATE TABLE C ... ENGINE MYISAM;

ALTER TABLE B ENGINE NDB;

SET @@ndb_table_no_logging = 0;

CREATE TABLE D ... ENGINE NDB;
ALTER TABLE C ENGINE NDB;

SET @@ndb_table_no_logging = 1;

After the previous sequence of events, tables A and B are not checkpointed; A was created with ENGINE NDB and B was altered to use NDB, both while ndb_table_no_logging was enabled. However, tables C and D are logged; C was altered to use NDB and D was created using ENGINE NDB, both while ndb_table_no_logging was disabled. Setting ndb_table_no_logging back to 1 or ON does not cause table C or D to be checkpointed.

ndb_table_temporary

When set to ON or 1, this variable causes NDB tables not to be written to disk: This means that no table schema files are created, and that the tables are not logged.

ndb_use_copying_alter_table

Forces NDB to use copying of tables in the event of problems with online ALTER TABLE operations. The default value is OFF.

ndb_use_exact_count

Forces NDB to use a count of records during SELECT COUNT(*) query planning to speed up this type of query. The default value is OFF, which allows for faster queries overall.

ndb_use_transactions

You can disable NDB transaction support by setting this variable's values to OFF (not recommended). The default is ON.

ndb_version

NDB engine version, as a composite integer.

ndb_version_string

NDB engine version in ndb-x.y.z format.

server_id_bits

The effective value of server_id if the server was started with the --server-id-bits option set to a nondefault value.

If the value of server_id greater than or equal to 2 to the power of server_id_bits, mysqld refuses to start.

This system variable is supported only by NDB Cluster. server_id_bits is not supported by the standard MySQL Server.

transaction_allow_batching

When set to 1 or ON, this variable enables batching of statements within the same transaction. To use this variable, autocommit must first be disabled by setting it to 0 or OFF; otherwise, setting transaction_allow_batching has no effect.

It is safe to use this variable with transactions that performs writes only, as having it enabled can lead to reads from the “before” image. You should ensure that any pending transactions are committed (using an explicit COMMIT if desired) before issuing a SELECT.

This variable is currently supported for NDB Cluster only.

ndbinfo_database

Shows the name used for the NDB information database; the default is ndbinfo. This is a read-only variable whose value is determined at compile time; you can set it by starting the server using --ndbinfo-database=name, which sets the value shown for this variable but does not actually change the name used for the NDB information database.

ndbinfo_max_bytes

Used in testing and debugging only.

ndbinfo_max_rows

Used in testing and debugging only.

ndbinfo_offline

Place the ndbinfo database into offline mode, in which tables and views can be opened even when they do not actually exist, or when they exist but have different definitions in NDB. No rows are returned from such tables (or views).

ndbinfo_show_hidden

Whether or not the ndbinfo database's underlying internal tables are shown in the mysql client. The default is OFF.

ndbinfo_table_prefix

The prefix used in naming the ndbinfo database's base tables (normally hidden, unless exposed by setting ndbinfo_show_hidden). This is a read-only variable whose default value is ndb$. You can start the server with the --ndbinfo-table-prefix option, but this merely sets the variable and does not change the actual prefix used to name the hidden base tables; the prefix itself is determined at compile time.

ndbinfo_version

Shows the version of the ndbinfo engine in use; read-only.

Handler_discover

The MySQL server can ask the NDBCLUSTER storage engine if it knows about a table with a given name. This is called discovery. Handler_discover indicates the number of times that tables have been discovered using this mechanism.

Ndb_api_bytes_sent_count_session

Amount of data (in bytes) sent to the data nodes in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_bytes_sent_count_slave

Amount of data (in bytes) sent to the data nodes by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_bytes_sent_count

Amount of data (in bytes) sent to the data nodes by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_bytes_received_count_session

Amount of data (in bytes) received from the data nodes in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_bytes_received_count_slave

Amount of data (in bytes) received from the data nodes by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_bytes_received_count

Amount of data (in bytes) received from the data nodes by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_event_data_count_injector

The number of row change events received by the NDB binlog injector thread.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_event_data_count

The number of row change events received by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_event_nondata_count_injector

The number of events received, other than row change events, by the NDB binary log injector thread.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_event_nondata_count

The number of events received, other than row change events, by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_event_bytes_count_injector

The number of bytes of events received by the NDB binlog injector thread.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_event_bytes_count

The number of bytes of events received by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_pk_op_count_session

The number of operations in this client session based on or using primary keys. This includes operations on blob tables, implicit unlock operations, and auto-increment operations, as well as user-visible primary key operations.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_pk_op_count_slave

The number of operations by this slave based on or using primary keys. This includes operations on blob tables, implicit unlock operations, and auto-increment operations, as well as user-visible primary key operations.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_pk_op_count

The number of operations by this MySQL Server (SQL node) based on or using primary keys. This includes operations on blob tables, implicit unlock operations, and auto-increment operations, as well as user-visible primary key operations.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_pruned_scan_count_session

The number of scans in this client session that have been pruned to a single partition.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_pruned_scan_count_slave

The number of scans by this slave that have been pruned to a single partition.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_pruned_scan_count

The number of scans by this MySQL Server (SQL node) that have been pruned to a single partition.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_range_scan_count_session

The number of range scans that have been started in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_range_scan_count_slave

The number of range scans that have been started by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_range_scan_count

The number of range scans that have been started by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_read_row_count_session

The total number of rows that have been read in this client session. This includes all rows read by any primary key, unique key, or scan operation made in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_read_row_count_slave

The total number of rows that have been read by this slave. This includes all rows read by any primary key, unique key, or scan operation made by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_read_row_count

The total number of rows that have been read by this MySQL Server (SQL node). This includes all rows read by any primary key, unique key, or scan operation made by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_scan_batch_count_session

The number of batches of rows received in this client session. 1 batch is defined as 1 set of scan results from a single fragment.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_scan_batch_count_slave

The number of batches of rows received by this slave. 1 batch is defined as 1 set of scan results from a single fragment.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_scan_batch_count

The number of batches of rows received by this MySQL Server (SQL node). 1 batch is defined as 1 set of scan results from a single fragment.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_table_scan_count_session

The number of table scans that have been started in this client session, including scans of internal tables,.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_table_scan_count_slave

The number of table scans that have been started by this slave, including scans of internal tables,.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_table_scan_count

The number of table scans that have been started by this MySQL Server (SQL node), including scans of internal tables,.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_abort_count_session

The number of transactions aborted in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_abort_count_slave

The number of transactions aborted by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_abort_count

The number of transactions aborted by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_close_count_session

The number of transactions closed in this client session. This value may be greater than the sum of Ndb_api_trans_commit_count_session and Ndb_api_trans_abort_count_session, since some transactions may have been rolled back.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_close_count_slave

The number of transactions closed by this slave. This value may be greater than the sum of Ndb_api_trans_commit_count_slave and Ndb_api_trans_abort_count_slave, since some transactions may have been rolled back.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_close_count

The number of transactions closed by this MySQL Server (SQL node). This value may be greater than the sum of Ndb_api_trans_commit_count and Ndb_api_trans_abort_count, since some transactions may have been rolled back.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_commit_count_session

The number of transactions committed in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_commit_count_slave

The number of transactions committed by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_commit_count

The number of transactions committed by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_local_read_row_count_session

The total number of rows that have been read in this client session. This includes all rows read by any primary key, unique key, or scan operation made in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_local_read_row_count_slave

The total number of rows that have been read by this slave. This includes all rows read by any primary key, unique key, or scan operation made by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_local_read_row_count

The total number of rows that have been read by this MySQL Server (SQL node). This includes all rows read by any primary key, unique key, or scan operation made by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_start_count_session

The number of transactions started in this client session.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_start_count_slave

The number of transactions started by this slave.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_trans_start_count

The number of transactions started by this MySQL Server (SQL node).

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_uk_op_count_session

The number of operations in this client session based on or using unique keys.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_uk_op_count_slave

The number of operations by this slave based on or using unique keys.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_uk_op_count

The number of operations by this MySQL Server (SQL node) based on or using unique keys.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_exec_complete_count_session

The number of times a thread has been blocked in this client session while waiting for execution of an operation to complete. This includes all execute() calls as well as implicit implicit executes for blob and auto-increment operations not visible to clients.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_exec_complete_count_slave

The number of times a thread has been blocked by this slave while waiting for execution of an operation to complete. This includes all execute() calls as well as implicit implicit executes for blob and auto-increment operations not visible to clients.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_exec_complete_count

The number of times a thread has been blocked by this MySQL Server (SQL node) while waiting for execution of an operation to complete. This includes all execute() calls as well as implicit implicit executes for blob and auto-increment operations not visible to clients.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_meta_request_count_session

The number of times a thread has been blocked in this client session waiting for a metadata-based signal, such as is expected for DDL requests, new epochs, and seizure of transaction records.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_meta_request_count_slave

The number of times a thread has been blocked by this slave waiting for a metadata-based signal, such as is expected for DDL requests, new epochs, and seizure of transaction records.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_meta_request_count

The number of times a thread has been blocked by this MySQL Server (SQL node) waiting for a metadata-based signal, such as is expected for DDL requests, new epochs, and seizure of transaction records.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_nanos_count_session

Total time (in nanoseconds) spent in this client session waiting for any type of signal from the data nodes.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_nanos_count_slave

Total time (in nanoseconds) spent by this slave waiting for any type of signal from the data nodes.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_nanos_count

Total time (in nanoseconds) spent by this MySQL Server (SQL node) waiting for any type of signal from the data nodes.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_scan_result_count_session

The number of times a thread has been blocked in this client session while waiting for a scan-based signal, such as when waiting for more results from a scan, or when waiting for a scan to close.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it relates to the current session only, and is not affected by any other clients of this mysqld.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_scan_result_count_slave

The number of times a thread has been blocked by this slave while waiting for a scan-based signal, such as when waiting for more results from a scan, or when waiting for a scan to close.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope. If this MySQL server does not act as a replication slave, or does not use NDB tables, this value is always 0.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_api_wait_scan_result_count

The number of times a thread has been blocked by this MySQL Server (SQL node) while waiting for a scan-based signal, such as when waiting for more results from a scan, or when waiting for a scan to close.

Although this variable can be read using either SHOW GLOBAL STATUS or SHOW SESSION STATUS, it is effectively global in scope.

For more information, see Section 18.5.15, “NDB API Statistics Counters and Variables”.

Ndb_cluster_node_id

If the server is acting as an NDB Cluster node, then the value of this variable its node ID in the cluster.

If the server is not part of an NDB Cluster, then the value of this variable is 0.

Ndb_config_from_host

If the server is part of an NDB Cluster, the value of this variable is the host name or IP address of the Cluster management server from which it gets its configuration data.

If the server is not part of an NDB Cluster, then the value of this variable is an empty string.

Ndb_config_from_port

If the server is part of an NDB Cluster, the value of this variable is the number of the port through which it is connected to the Cluster management server from which it gets its configuration data.

If the server is not part of an NDB Cluster, then the value of this variable is 0.

Ndb_conflict_fn_max

Used in NDB Cluster Replication conflict resolution, this variable shows the number of times that a row was not applied on the current SQL node due to “greatest timestamp wins” conflict resolution since the last time that this mysqld was started.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_fn_old

Used in NDB Cluster Replication conflict resolution, this variable shows the number of times that a row was not applied as the result of “same timestamp wins” conflict resolution on a given mysqld since the last time it was restarted.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_fn_epoch

Used in NDB Cluster Replication conflict resolution, this variable shows the number of rows found to be in conflict using NDB$EPOCH() conflict resolution on a given mysqld since the last time it was restarted.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_fn_epoch_trans

Used in NDB Cluster Replication conflict resolution, this variable shows the number of rows found to be in conflict using NDB$EPOCH_TRANS() conflict resolution on a given mysqld since the last time it was restarted.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_trans_row_conflict_count

Used in NDB Cluster Replication conflict resolution, this status variable shows the number of rows found to be directly in-conflict by a transactional conflict function on a given mysqld since the last time it was restarted.

Currently, the only transactional conflict detection function supported by NDB Cluster is NDB$EPOCH_TRANS(), so this status variable is effectively the same as Ndb_conflict_fn_epoch_trans.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_trans_row_reject_count

Used in NDB Cluster Replication conflict resolution, this status variable shows the total number of rows realigned due to being determined as conflicting by a transactional conflict detection function. This includes not only Ndb_conflict_trans_row_conflict_count, but any rows in or dependent on conflicting transactions.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_trans_reject_count

Used in NDB Cluster Replication conflict resolution, this status variable shows the number of transactions found to be in conflict by a transactional conflict detection function.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_trans_detect_iter_count

Used in NDB Cluster Replication conflict resolution, this shows the number of internal iterations required to commit an epoch transaction. Should be (slightly) greater than or equal to Ndb_conflict_trans_conflict_commit_count.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_conflict_trans_conflict_commit_count

Used in NDB Cluster Replication conflict resolution, this shows the number of epoch transactions committed after they required transactional conflict handling.

For more information, see Section 18.6.11, “NDB Cluster Replication Conflict Resolution”.

Ndb_execute_count

Provides the number of round trips to the NDB kernel made by operations.

Ndb_number_of_data_nodes

If the server is part of an NDB Cluster, the value of this variable is the number of data nodes in the cluster.

If the server is not part of an NDB Cluster, then the value of this variable is 0.

Ndb_pushed_queries_defined

The total number of joins pushed down to the NDB kernel for distributed handling on the data nodes. Note that joins tested using EXPLAIN that can be pushed down contribute to this number. Added in NDB 7.2.0.

Ndb_pushed_queries_dropped

The number of joins that were pushed down to the NDB kernel but that could not be handled there. Added in NDB 7.2.0.

Ndb_pushed_queries_executed

The number of joins successfully pushed down to NDB and executed there. Added in NDB 7.2.0.

Ndb_pushed_reads

The number of rows returned to mysqld from the NDB kernel by joins that were pushed down. Note that executing EXPLAIN on joins that can be pushed down to NDB does not add to this number. Added in NDB 7.2.0.

Ndb_pruned_scan_count

This variable holds a count of the number of scans executed by NDBCLUSTER since the NDB Cluster was last started where NDBCLUSTER was able to use partition pruning.

Using this variable together with Ndb_scan_count can be helpful in schema design to maximize the ability of the server to prune scans to a single table partition, thereby involving only a single data node.

Ndb_scan_count

This variable holds a count of the total number of scans executed by NDBCLUSTER since the NDB Cluster was last started.