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5.2.5 NDB Cluster mysqld Option and Variable Reference

The following table provides a list of the command-line options, server and status variables applicable within mysqld when it is running as an SQL node in an NDB Cluster. For a table showing all command-line options, server and status variables available for use with mysqld, see Server Option, System Variable, and Status Variable Reference.

  • Com_show_ndb_status: Count of SHOW NDB STATUS statements

  • Handler_discover: Number of times that tables have been discovered

  • ndb-batch-size: Size (in bytes) to use for NDB transaction batches

  • ndb-blob-read-batch-bytes: Specifies size in bytes that large BLOB reads should be batched into. 0 = no limit.

  • ndb-blob-write-batch-bytes: Specifies size in bytes that large BLOB writes should be batched into. 0 = no limit.

  • ndb-cluster-connection-pool: Number of connections to the cluster used by MySQL

  • ndb-cluster-connection-pool-nodeids: Comma-separated list of node IDs for connections to the cluster used by MySQL; the number of nodes in the list must be the same as the value set for --ndb-cluster-connection-pool

  • ndb-connectstring: Point to the management server that distributes the cluster configuration

  • ndb-default-column-format: Use this value (FIXED or DYNAMIC) by default for COLUMN_FORMAT and ROW_FORMAT options when creating or adding columns to a table.

  • ndb-deferred-constraints: Specifies that constraint checks on unique indexes (where these are supported) should be deferred until commit time. Not normally needed or used; for testing purposes only.

  • ndb-distribution: Default distribution for new tables in NDBCLUSTER (KEYHASH or LINHASH, default is KEYHASH)

  • ndb-log-apply-status: Cause a MySQL server acting as a slave to log mysql.ndb_apply_status updates received from its immediate master in its own binary log, using its own server ID. Effective only if the server is started with the --ndbcluster option.

  • ndb-log-empty-epochs: When enabled, causes epochs in 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.

  • ndb-log-empty-update: When enabled, 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.

  • ndb-log-exclusive-reads: Log primary key reads with exclusive locks; allow conflict resolution based on read conflicts

  • ndb-log-orig: Log originating server id and epoch in mysql.ndb_binlog_index table

  • ndb-log-transaction-id: Write NDB transaction IDs in the binary log. Requires --log-bin-v1-events=OFF.

  • ndb-mgmd-host: Set the host (and port, if desired) for connecting to management server

  • ndb-nodeid: NDB Cluster node ID for this MySQL server

  • ndb-recv-thread-activation-threshold: Activation threshold when receive thread takes over the polling of the cluster connection (measured in concurrently active threads)

  • ndb-recv-thread-cpu-mask: CPU mask for locking receiver threads to specific CPUs; specified as hexadecimal. See documentation for details.

  • ndb-transid-mysql-connection-map: Enable or disable the ndb_transid_mysql_connection_map plugin; that is, enable or disable the INFORMATION_SCHEMA table having that name

  • ndb-wait-connected: Time (in seconds) for the MySQL server to wait for connection to cluster management and data nodes before accepting MySQL client connections

  • ndb-wait-setup: Time (in seconds) for the MySQL server to wait for NDB engine setup to complete

  • ndb-allow-copying-alter-table: Set to OFF to keep ALTER TABLE from using copying operations on NDB tables

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

  • Ndb_api_bytes_received_count_session: Amount of data (in bytes) received from the data nodes in this client session

  • Ndb_api_bytes_received_count_slave: Amount of data (in bytes) received from the data nodes by this slave

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

  • Ndb_api_bytes_sent_count_slave: Amount of data (in bytes) sent to the data nodes by this slave

  • Ndb_api_event_bytes_count_injector: Number of bytes of events received by the NDB binary log injector thread

  • Ndb_api_event_data_count_injector: Number of row change events received by the NDB binary log injector thread

  • Ndb_api_event_nondata_count_injector: Number of events received, other than row change events, by the NDB binary log injector thread

  • Ndb_api_pk_op_count: Number of operations based on or using primary keys by this MySQL Server (SQL node)

  • Ndb_api_pk_op_count_session: Number of operations based on or using primary keys in this client session

  • Ndb_api_pk_op_count_slave: Number of operations based on or using primary keys by this slave

  • Ndb_api_pruned_scan_count: Number of scans that have been pruned to a single partition by this MySQL Server (SQL node)

  • Ndb_api_pruned_scan_count_session: Number of scans that have been pruned to a single partition in this client session

  • Ndb_api_range_scan_count_slave: Number of range scans that have been started by this slave

  • Ndb_api_read_row_count: Total number of rows that have been read by this MySQL Server (SQL node)

  • Ndb_api_read_row_count_session: Total number of rows that have been read in this client session

  • Ndb_api_scan_batch_count_slave: Number of batches of rows received by this slave

  • Ndb_api_table_scan_count: Number of table scans that have been started, including scans of internal tables, by this MySQL Server (SQL node)

  • Ndb_api_table_scan_count_session: Number of table scans that have been started, including scans of internal tables, in this client session

  • Ndb_api_trans_abort_count: Number of transactions aborted by this MySQL Server (SQL node)

  • Ndb_api_trans_abort_count_session: Number of transactions aborted in this client session

  • Ndb_api_trans_abort_count_slave: Number of transactions aborted by this slave

  • Ndb_api_trans_close_count: Number of transactions aborted (may be greater than the sum of TransCommitCount and TransAbortCount) by this MySQL Server (SQL node)

  • Ndb_api_trans_close_count_session: Number of transactions aborted (may be greater than the sum of TransCommitCount and TransAbortCount) in this client session

  • Ndb_api_trans_close_count_slave: Number of transactions aborted (may be greater than the sum of TransCommitCount and TransAbortCount) by this slave

  • Ndb_api_trans_commit_count: Number of transactions committed by this MySQL Server (SQL node)

  • Ndb_api_trans_commit_count_session: Number of transactions committed in this client session

  • Ndb_api_trans_commit_count_slave: Number of transactions committed by this slave

  • Ndb_api_trans_local_read_row_count_slave: Total number of rows that have been read by this slave

  • Ndb_api_trans_start_count: Number of transactions started by this MySQL Server (SQL node)

  • Ndb_api_trans_start_count_session: Number of transactions started in this client session

  • Ndb_api_trans_start_count_slave: Number of transactions started by this slave

  • Ndb_api_uk_op_count: Number of operations based on or using unique keys by this MySQL Server (SQL node)

  • Ndb_api_uk_op_count_slave: Number of operations based on or using unique keys by this slave

  • Ndb_api_wait_exec_complete_count: Number of times thread has been blocked while waiting for execution of an operation to complete by this MySQL Server (SQL node)

  • Ndb_api_wait_exec_complete_count_session: Number of times thread has been blocked while waiting for execution of an operation to complete in this client session

  • Ndb_api_wait_exec_complete_count_slave: Number of times thread has been blocked while waiting for execution of an operation to complete by this slave

  • Ndb_api_wait_meta_request_count: Number of times thread has been blocked waiting for a metadata-based signal by this MySQL Server (SQL node)

  • Ndb_api_wait_meta_request_count_session: Number of times thread has been blocked waiting for a metadata-based signal in this client session

  • Ndb_api_wait_nanos_count: Total time (in nanoseconds) spent waiting for some type of signal from the data nodes by this MySQL Server (SQL node)

  • Ndb_api_wait_nanos_count_session: Total time (in nanoseconds) spent waiting for some type of signal from the data nodes in this client session

  • Ndb_api_wait_nanos_count_slave: Total time (in nanoseconds) spent waiting for some type of signal from the data nodes by this slave

  • Ndb_api_wait_scan_result_count: Number of times thread has been blocked while waiting for a scan-based signal by this MySQL Server (SQL node)

  • Ndb_api_wait_scan_result_count_session: Number of times thread has been blocked while waiting for a scan-based signal in this client session

  • Ndb_api_wait_scan_result_count_slave: Number of times thread has been blocked while waiting for a scan-based signal by this slave

  • ndb_autoincrement_prefetch_sz: NDB auto-increment prefetch size

  • ndb_cache_check_time: Number of milliseconds between checks of cluster SQL nodes made by the MySQL query cache

  • ndb_clear_apply_status: Causes RESET SLAVE to clear all rows from the ndb_apply_status table; ON by default

  • 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

  • Ndb_config_from_host: The host name or IP address of the Cluster management server Formerly Ndb_connected_host

  • Ndb_config_from_port: The port for connecting to Cluster management server. Formerly Ndb_connected_port

  • Ndb_conflict_fn_epoch_trans: Number of rows that have been found in conflict by the NDB$EPOCH_TRANS() conflict detection function

  • Ndb_conflict_fn_max: If the server is part of an NDB Cluster involved in cluster replication, the value of this variable indicates the number of times that conflict resolution based on "greater timestamp wins" has been applied

  • Ndb_conflict_fn_old: If the server is part of an NDB Cluster involved in cluster replication, the value of this variable indicates the number of times that "same timestamp wins" conflict resolution has been applied

  • Ndb_conflict_trans_detect_iter_count: Number of internal iterations required to commit an epoch transaction. Should be (slightly) greater than or equal to Ndb_conflict_trans_conflict_commit_count

  • Ndb_conflict_trans_row_reject_count: Total number of rows realigned after being found in conflict by a transactional conflict function. Includes Ndb_conflict_trans_row_conflict_count and any rows included in or dependent on conflicting transactions.

  • ndb_data_node_neighbour: Specifies cluster data node "closest" to this MySQL Server, for transaction hinting and fully replicated tables

  • ndb_default_column_format: Sets default row format and column format (FIXED or DYNAMIC) used for new NDB tables

  • ndb_deferred_constraints: Specifies that constraint checks should be deferred (where these are supported). Not normally needed or used; for testing purposes only.

  • ndb_distribution: Default distribution for new tables in NDBCLUSTER (KEYHASH or LINHASH, default is KEYHASH)

  • ndb_eventbuffer_free_percent: Percentage of free memory that should be available in event buffer before resumption of buffering, after reaching limit set by ndb_eventbuffer_max_alloc

  • ndb_eventbuffer_max_alloc: Maximum memory that can be allocated for buffering events by the NDB API. Defaults to 0 (no limit).

  • ndb_extra_logging: Controls logging of NDB Cluster schema, connection, and data distribution events in the MySQL error log

  • ndb_force_send: Forces sending of buffers to NDB immediately, without waiting for other threads

  • ndb_fully_replicated: Whether new NDB tables are fully replicated

  • ndb_index_stat_enable: Use NDB index statistics in query optimization

  • ndb_index_stat_option: Comma-separated list of tunable options for NDB index statistics; the list should contain no spaces

  • ndb_join_pushdown: Enables pushing down of joins to data nodes

  • ndb_log_apply_status: Whether or not a MySQL server acting as a slave logs mysql.ndb_apply_status updates received from its immediate master in its own binary log, using its own server ID

  • ndb_log_bin: Write updates to NDB tables in the binary log. Effective only if binary logging is enabled with --log-bin.

  • ndb_log_binlog_index: Insert mapping between epochs and binary log positions into the ndb_binlog_index table. Defaults to ON. Effective only if binary logging is enabled on the server.

  • ndb_log_empty_epochs: When enabled, epochs in which there were no changes are written to the ndb_apply_status and ndb_binlog_index tables, even when log_slave_updates is enabled

  • ndb_log_empty_update: When enabled, updates which produce no changes are written to the ndb_apply_status and ndb_binlog_index tables, even when log_slave_updates is enabled

  • ndb_log_exclusive_reads: Log primary key reads with exclusive locks; allow conflict resolution based on read conflicts

  • ndb_log_orig: Whether the id and epoch of the originating server are recorded in the mysql.ndb_binlog_index table. Set using the --ndb-log-orig option when starting mysqld.

  • ndb_log_transaction_id: Whether NDB transaction IDs are written into the binary log (Read-only.)

  • ndb-log-update-minimal: Log updates in a minimal format.

  • ndb_log_updated_only: Log complete rows (ON) or updates only (OFF)

  • 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

  • ndb_optimization_delay: Sets the number of milliseconds to wait between processing sets of rows by OPTIMIZE TABLE on NDB tables

  • ndb_optimized_node_selection: Determines how an SQL node chooses a cluster data node to use as transaction coordinator

  • Ndb_pushed_queries_defined: Number of joins that API nodes have attempted to push down to the data nodes

  • Ndb_pushed_queries_executed: Number of joins successfully pushed down and executed on the data nodes

  • ndb_read_backup: Enable read from any replica

  • ndb_recv_thread_activation_threshold: Activation threshold when receive thread takes over the polling of the cluster connection (measured in concurrently active threads)

  • ndb_recv_thread_cpu_mask: CPU mask for locking receiver threads to specific CPUs; specified as hexadecimal. See documentation for details.

  • ndb_report_thresh_binlog_epoch_slip: NDB 7.5.4 and later: Threshold for number of epochs completely buffered, but not yet consumed by binlog injector thread which when exceeded generates BUFFERED_EPOCHS_OVER_THRESHOLD event buffer status message; prior to NDB 7.5.4: Threshold for number of epochs to lag behind before reporting binary log status

  • ndb_report_thresh_binlog_mem_usage: This is a threshold on the percentage of free memory remaining before reporting binary log status

  • Ndb_scan_count: The total number of scans executed by NDB since the cluster was last started

  • ndb_show_foreign_key_mock_tables: Show the mock tables used to support foreign_key_checks=0

  • ndb_slave_conflict_role: Role for slave to play in conflict detection and resolution. Value is one of PRIMARY, SECONDARY, PASS, or NONE (default). Can be changed only when slave SQL thread is stopped. See documentation for further information.

  • Ndb_slave_max_replicated_epoch: The most recently committed NDB epoch on this slave. When this value is greater than or equal to Ndb_conflict_last_conflict_epoch, no conflicts have yet been detected.

  • Ndb_system_name: Configured cluster system name; empty if server not connected to NDB

  • ndb_table_no_logging: NDB tables created when this setting is enabled are not checkpointed to disk (although table schema files are created). The setting in effect when the table is created with or altered to use NDBCLUSTER persists for the lifetime of the table.

  • ndb_table_temporary: NDB tables are not persistent on disk: no schema files are created and the tables are not logged

  • ndb_use_exact_count: Use exact row count when planning queries

  • ndb_use_transactions: Forces NDB to use a count of records during SELECT COUNT(*) query planning to speed up this type of query

  • ndb_version: Shows build and NDB engine version as an integer

  • ndb_version_string: Shows build information including NDB engine version in ndb-x.y.z format

  • ndbcluster: Enable NDB Cluster (if this version of MySQL supports it) Disabled by --skip-ndbcluster

  • ndbinfo_database: The name used for the NDB information database; read only

  • ndbinfo_max_bytes: Used for debugging only

  • ndbinfo_max_rows: Used for debugging only

  • ndbinfo_offline: Put the ndbinfo database into offline mode, in which no rows are returned from tables or views

  • ndbinfo_show_hidden: Whether to show ndbinfo internal base tables in the mysql client. The default is OFF.

  • ndbinfo_table_prefix: The prefix to use for naming ndbinfo internal base tables

  • ndbinfo_version: The version of the ndbinfo engine; read only

  • server-id-bits: Sets the number of least significant bits in the server_id actually used for identifying the server, permitting NDB API applications to store application data in the most significant bits. server_id must be less than 2 to the power of this value.

  • 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

  • slave_allow_batching: Turns update batching on and off for a replication slave

  • transaction_allow_batching: Allows batching of statements within a transaction. Disable AUTOCOMMIT to use.


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