17.3.4.1. MySQL 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 a MySQL Cluster. For a table showing all command-line options, server and status variables available for use with mysqld, see Section 5.1.1, "Server Option and Variable Reference".

Table 17.9. MySQL Cluster mysqld Options and Variables: MySQLCluster NDB 7.3

Option or Variable Name	Command Line	System Variable	Scope
Option or Variable Name	Option File	Status Variable	Dynamic
Notes
`Handler_discover`	N	N	Both
`Handler_discover`	N	Y	N
The number of times that tables have been discovered
`Ndb_api_wait_exec_complete_count_session`	N	N	Session
`Ndb_api_wait_exec_complete_count_session`	N	Y	N
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`	N	N	Global
`Ndb_api_wait_exec_complete_count_slave`	N	Y	N
Number of times thread has been blocked while waiting for execution of an operation to complete by this slave.
`Ndb_api_wait_exec_complete_count`	N	N	Global
`Ndb_api_wait_exec_complete_count`	N	Y	N
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_scan_result_count_session`	N	N	Session
`Ndb_api_wait_scan_result_count_session`	N	Y	N
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`	N	N	Global
`Ndb_api_wait_scan_result_count_slave`	N	Y	N
Number of times thread has been blocked while waiting for a scan-based signal by this slave.
`Ndb_api_wait_scan_result_count`	N	N	Global
`Ndb_api_wait_scan_result_count`	N	Y	N
Number of times thread has been blocked while waiting for a scan-based signal by this MySQL Server (SQL node).
`Ndb_api_wait_meta_request_count_session`	N	N	Session
`Ndb_api_wait_meta_request_count_session`	N	Y	N
Number of times thread has been blocked waiting for a metadata-based signal in this client session.
`Ndb_api_wait_meta_request_count_slave`	N	N	Global
`Ndb_api_wait_meta_request_count_slave`	N	Y	N
Number of times thread has been blocked waiting for a metadata-based signal by this slave.
`Ndb_api_wait_meta_request_count`	N	N	Global
`Ndb_api_wait_meta_request_count`	N	Y	N
Number of times thread has been blocked waiting for a metadata-based signal by this MySQL Server (SQL node).
`Ndb_api_wait_nanos_count_session`	N	N	Session
`Ndb_api_wait_nanos_count_session`	N	Y	N
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`	N	N	Global
`Ndb_api_wait_nanos_count_slave`	N	Y	N
Total time (in nanoseconds) spent waiting for some type of signal from the data nodes by this slave.
`Ndb_api_wait_nanos_count`	N	N	Global
`Ndb_api_wait_nanos_count`	N	Y	N
Total time (in nanoseconds) spent waiting for some type of signal from the data nodes by this MySQL Server (SQL node).
`Ndb_api_bytes_sent_count_session`	N	N	Session
`Ndb_api_bytes_sent_count_session`	N	Y	N
Amount of data (in bytes) sent to the data nodes in this client session.
`Ndb_api_bytes_sent_count_slave`	N	N	Global
`Ndb_api_bytes_sent_count_slave`	N	Y	N
Amount of data (in bytes) sent to the data nodes by this slave.
`Ndb_api_bytes_sent_count`	N	N	Global
`Ndb_api_bytes_sent_count`	N	Y	N
Amount of data (in bytes) sent to the data nodes by this MySQL Server (SQL node).
`Ndb_api_bytes_received_count_session`	N	N	Session
`Ndb_api_bytes_received_count_session`	N	Y	N
Amount of data (in bytes) received from the data nodes in this client session.
`Ndb_api_bytes_received_count_slave`	N	N	Global
`Ndb_api_bytes_received_count_slave`	N	Y	N
Amount of data (in bytes) received from the data nodes by this slave.
`Ndb_api_bytes_received_count`	N	N	Global
`Ndb_api_bytes_received_count`	N	Y	N
Amount of data (in bytes) received from the data nodes by this MySQL Server (SQL node).
`Ndb_api_trans_start_count_session`	N	N	Session
`Ndb_api_trans_start_count_session`	N	Y	N
Number of transactions started in this client session.
`Ndb_api_trans_start_count_slave`	N	N	Global
`Ndb_api_trans_start_count_slave`	N	Y	N
Number of transactions started by this slave.
`Ndb_api_trans_start_count`	N	N	Global
`Ndb_api_trans_start_count`	N	Y	N
Number of transactions started by this MySQL Server (SQL node).
`Ndb_api_trans_commit_count_session`	N	N	Session
`Ndb_api_trans_commit_count_session`	N	Y	N
Number of transactions committed in this client session.
`Ndb_api_trans_commit_count_slave`	N	N	Global
`Ndb_api_trans_commit_count_slave`	N	Y	N
Number of transactions committed by this slave.
`Ndb_api_trans_commit_count`	N	N	Global
`Ndb_api_trans_commit_count`	N	Y	N
Number of transactions committed by this MySQL Server (SQL node).
`Ndb_api_trans_abort_count_session`	N	N	Session
`Ndb_api_trans_abort_count_session`	N	Y	N
Number of transactions aborted in this client session.
`Ndb_api_trans_abort_count_slave`	N	N	Global
`Ndb_api_trans_abort_count_slave`	N	Y	N
Number of transactions aborted by this slave.
`Ndb_api_trans_abort_count`	N	N	Global
`Ndb_api_trans_abort_count`	N	Y	N
Number of transactions aborted by this MySQL Server (SQL node).
`Ndb_api_trans_close_count_session`	N	N	Session
`Ndb_api_trans_close_count_session`	N	Y	N
Number of transactions aborted (may be greater than the sum of TransCommitCount and TransAbortCount) in this client session.
`Ndb_api_trans_close_count_slave`	N	N	Global
`Ndb_api_trans_close_count_slave`	N	Y	N
Number of transactions aborted (may be greater than the sum of TransCommitCount and TransAbortCount) by this slave.
`Ndb_api_trans_close_count`	N	N	Global
`Ndb_api_trans_close_count`	N	Y	N
Number of transactions aborted (may be greater than the sum of TransCommitCount and TransAbortCount) by this MySQL Server (SQL node).
`Ndb_api_pk_op_count_session`	N	N	Session
`Ndb_api_pk_op_count_session`	N	Y	N
Number of operations based on or using primary keys in this client session.
`Ndb_api_pk_op_count_slave`	N	N	Global
`Ndb_api_pk_op_count_slave`	N	Y	N
Number of operations based on or using primary keys by this slave.
`Ndb_api_pk_op_count`	N	N	Global
`Ndb_api_pk_op_count`	N	Y	N
Number of operations based on or using primary keys by this MySQL Server (SQL node).
`Ndb_api_uk_op_count_session`	N	N	Session
`Ndb_api_uk_op_count_session`	N	Y	N
Number of operations based on or using unique keys in this client session.
`Ndb_api_uk_op_count_slave`	N	N	Global
`Ndb_api_uk_op_count_slave`	N	Y	N
Number of operations based on or using unique keys by this slave.
`Ndb_api_uk_op_count`	N	N	Global
`Ndb_api_uk_op_count`	N	Y	N
Number of operations based on or using unique keys by this MySQL Server (SQL node).
`Ndb_api_table_scan_count_session`	N	N	Session
`Ndb_api_table_scan_count_session`	N	Y	N
Number of table scans that have been started, including scans of internal tables, in this client session.
`Ndb_api_table_scan_count_slave`	N	N	Global
`Ndb_api_table_scan_count_slave`	N	Y	N
Number of table scans that have been started, including scans of internal tables, by this slave.
`Ndb_api_table_scan_count`	N	N	Global
`Ndb_api_table_scan_count`	N	Y	N
Number of table scans that have been started, including scans of internal tables, by this MySQL Server (SQL node).
`Ndb_api_range_scan_count_session`	N	N	Session
`Ndb_api_range_scan_count_session`	N	Y	N
Number of range scans that have been started in this client session.
`Ndb_api_range_scan_count_slave`	N	N	Global
`Ndb_api_range_scan_count_slave`	N	Y	N
Number of range scans that have been started by this slave.
`Ndb_api_range_scan_count`	N	N	Global
`Ndb_api_range_scan_count`	N	Y	N
Number of range scans that have been started by this MySQL Server (SQL node).
`Ndb_api_pruned_scan_count_session`	N	N	Session
`Ndb_api_pruned_scan_count_session`	N	Y	N
Number of scans that have been pruned to a single partition in this client session.
`Ndb_api_pruned_scan_count_slave`	N	N	Global
`Ndb_api_pruned_scan_count_slave`	N	Y	N
Number of scans that have been pruned to a single partition by this slave.
`Ndb_api_pruned_scan_count`	N	N	Global
`Ndb_api_pruned_scan_count`	N	Y	N
Number of scans that have been pruned to a single partition by this MySQL Server (SQL node).
`Ndb_api_scan_batch_count_session`	N	N	Session
`Ndb_api_scan_batch_count_session`	N	Y	N
Number of batches of rows received in this client session.
`Ndb_api_scan_batch_count_slave`	N	N	Global
`Ndb_api_scan_batch_count_slave`	N	Y	N
Number of batches of rows received by this slave.
`Ndb_api_scan_batch_count`	N	N	Global
`Ndb_api_scan_batch_count`	N	Y	N
Number of batches of rows received by this MySQL Server (SQL node).
`Ndb_api_read_row_count_session`	N	N	Session
`Ndb_api_read_row_count_session`	N	Y	N
Total number of rows that have been read in this client session.
`Ndb_api_read_row_count_slave`	N	N	Global
`Ndb_api_read_row_count_slave`	N	Y	N
Total number of rows that have been read by this slave.
`Ndb_api_read_row_count`	N	N	Global
`Ndb_api_read_row_count`	N	Y	N
Total number of rows that have been read by this MySQL Server (SQL node).
`Ndb_api_trans_local_read_row_count_session`	N	N	Session
`Ndb_api_trans_local_read_row_count_session`	N	Y	N
Total number of rows that have been read in this client session.
`Ndb_api_trans_local_read_row_count_slave`	N	N	Global
`Ndb_api_trans_local_read_row_count_slave`	N	Y	N
Total number of rows that have been read by this slave.
`Ndb_api_trans_local_read_row_count`	N	N	Global
`Ndb_api_trans_local_read_row_count`	N	Y	N
Total number of rows that have been read by this MySQL Server (SQL node).
`Ndb_api_event_data_count_injector`	N	N	Global
`Ndb_api_event_data_count_injector`	N	Y	N
Number of row change events received by the NDB binlog injector thread.
`Ndb_api_event_data_count`	N	N	Global
`Ndb_api_event_data_count`	N	Y	N
Number of row change events received by this MySQL Server (SQL node).
`Ndb_api_event_nondata_count_injector`	N	N	Global
`Ndb_api_event_nondata_count_injector`	N	Y	N
Number of events received, other than row change events, by the NDB binlog injector thread.
`Ndb_api_event_nondata_count`	N	N	Global
`Ndb_api_event_nondata_count`	N	Y	N
Number of events received, other than row change events, by this MySQL Server (SQL node).
`Ndb_api_event_bytes_count_injector`	N	N	Global
`Ndb_api_event_bytes_count_injector`	N	Y	N
Number of bytes of events received by the NDB binlog injector thread.
`Ndb_api_event_bytes_count`	N	N	Global
`Ndb_api_event_bytes_count`	N	Y	N
Number of bytes of events received by this MySQL Server (SQL node).
`Ndb_number_of_data_nodes`	N	N	Global
`Ndb_number_of_data_nodes`	N	Y	N
If the server is part of a MySQL Cluster, the value of this variable is the number of data nodes in the cluster
`Ndb_conflict_fn_max`	N	N	Global
`Ndb_conflict_fn_max`	N	Y	N
If the server is part of a MySQL 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`	N	N	Global
`Ndb_conflict_fn_old`	N	Y	N
If the server is part of a MySQL 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_fn_epoch`	N	N	Global
`Ndb_conflict_fn_epoch`	N	Y	N
Number of rows that have been found in conflict by the NDB$EPOCH() conflict detection function
`Ndb_conflict_fn_epoch_trans`	N	N	Global
`Ndb_conflict_fn_epoch_trans`	N	Y	N
Number of rows that have been found in conflict by the NDB$EPOCH_TRANS() conflict detection function
`Ndb_conflict_trans_row_conflict_count`	N	N	Global
`Ndb_conflict_trans_row_conflict_count`	N	Y	N
Number of rows found to be in conflict by a transactional conflict function
`Ndb_conflict_trans_row_reject_count`	N	N	Global
`Ndb_conflict_trans_row_reject_count`	N	Y	N
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_conflict_trans_reject_count`	N	N	Global
`Ndb_conflict_trans_reject_count`	N	Y	N
Number of transactions rejected after being found in conflict by a transactional conflict function.
`Ndb_conflict_trans_detect_iter_count`	N	N	Global
`Ndb_conflict_trans_detect_iter_count`	N	Y	N
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.
`Ndb_conflict_trans_conflict_commit_count`	N	N	Global
`Ndb_conflict_trans_conflict_commit_count`	N	Y	N
The number of epoch transactions committed after requiring transactional conflict handling.
`ndb_optimization_delay`	N	Y	Global
`ndb_optimization_delay`	N	N	Y
Sets the number of milliseconds to wait between processing sets of rows by OPTIMIZE TABLE on NDB tables.
`ndb_table_temporary`	N	Y	Session
`ndb_table_temporary`	N	N	Y
NDB tables are not persistent on disk: no schema files are created and the tables are not logged
`ndb_table_no_logging`	N	Y	Session
`ndb_table_no_logging`	N	N	Y
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_autoincrement_prefetch_sz`	Y	Y	Both
`ndb_autoincrement_prefetch_sz`	Y	N	Y
NDB auto-increment prefetch size
`ndb-batch-size`	Y	Y	Global
`ndb-batch-size`	Y	N	N
The size (in bytes) to use for NDB transaction batches
`ndb-blob-read-batch-bytes`	Y	Y	Both
`ndb-blob-read-batch-bytes`	Y	N	Y
Specifies the size in bytes that large BLOB reads should be batched into. 0 = no limit.
`ndb-blob-write-batch-bytes`	Y	Y	Both
`ndb-blob-write-batch-bytes`	Y	N	Y
Specifies the size in bytes that large BLOB writes should be batched into. 0 = no limit.
`ndb_cache_check_time`	Y	Y	Global
`ndb_cache_check_time`	Y	N	Y
The number of milliseconds between checks of cluster SQL nodes made by the MySQL query cache
`ndb-cluster-connection-pool`	Y	Y	Global
`ndb-cluster-connection-pool`	Y	Y	N
The number of connections to the cluster used by MySQL
`ndb_join_pushdown`	N	Y	Global
`ndb_join_pushdown`	N	N	N
Enables pushing down of joins to data nodes
`Ndb_execute_count`	N	N	Global
`Ndb_execute_count`	N	Y	N
Provides the number of round trips to the NDB kernel made by operations
`Ndb_scan_count`	N	N	Global
`Ndb_scan_count`	N	Y	N
The total number of scans executed by NDB since the cluster was last started
`Ndb_pruned_scan_count`	N	N	Global
`Ndb_pruned_scan_count`	N	Y	N
The number of scans executed by NDB since the cluster was last started where partition pruning could be used
`ndb-connectstring`	Y	N
`ndb-connectstring`	Y	N	N
The management server that distributes the cluster configuration
`ndb_extra_logging`	Y	Y	Global
`ndb_extra_logging`	Y	N	Y
Controls logging of MySQL Cluster schema, connection, and data distribution events in the MySQL error log
`ndb_force_send`	Y	Y	Both
`ndb_force_send`	Y	N	Y
Forces sending of buffers to NDB immediately, without waiting for other threads
`ndb_use_exact_count`	N	Y	Both
`ndb_use_exact_count`	N	N	Y
Use exact row count when planning queries
`ndb-log-apply-status`	Y	Y	Global
`ndb-log-apply-status`	Y	N	N
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_bin`	Y	Y	Both
`ndb_log_bin`	N	N	Y
Write updates to NDB tables in the binary log. Effective only if binary logging is enabled with --log-bin.
`ndb_log_binlog_index`	Y	Y	Global
`ndb_log_binlog_index`	N	N	Y
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-orig`	Y	Y	Global
`ndb-log-orig`	Y	N	N
Log originating server id and epoch in mysql.ndb_binlog_index table.
`ndb-log-transaction-id`	Y	Y	Global
`ndb-log-transaction-id`	Y	N	N
Write NDB transaction IDs in the binary log. Requires --log-bin-v1-events=OFF.
`ndb_log_transaction_id`	N	Y	Global
`ndb_log_transaction_id`	N	N	N
Whether NDB transaction IDs are written into the binary log. (Read-only.)
`ndb_log_updated_only`	Y	Y	Global
`ndb_log_updated_only`	Y	N	Y
Log complete rows (ON) or updates only (OFF)
`ndb-log-update-as-write`	Y	Y	Global
`ndb-log-update-as-write`	Y	N	Y
Toggles logging of updates on the master between updates (OFF) and writes (ON)
`ndb-log-empty-epochs`	Y	Y	Global
`ndb-log-empty-epochs`	Y	N	Y
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_epochs`	Y	Y	Global
`ndb_log_empty_epochs`	Y	N	Y
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-transid-mysql-connection-map`	Y	N
`ndb-transid-mysql-connection-map`	N	N	N
Enable or disable the ndb_transid_mysql_connection_map plugin; that is, enable or disable the INFORMATION_SCHEMA table having that name.
`Ndb_pushed_reads`	N	N	Global
`Ndb_pushed_reads`	N	Y	N
Number of reads executed on the data nodes by pushed-down joins
`Ndb_pushed_queries_defined`	N	N	Global
`Ndb_pushed_queries_defined`	N	Y	N
Number of joins that API nodes have attempted to push down to the data nodes
`Ndb_pushed_queries_dropped`	N	N	Global
`Ndb_pushed_queries_dropped`	N	Y	N
Number of joins that API nodes have tried to push down, but failed
`Ndb_pushed_queries_executed`	N	N	Global
`Ndb_pushed_queries_executed`	N	Y	N
Number of joins successfully pushed down and executed on the data nodes
`ndb-nodeid`	Y	N	Global
`ndb-nodeid`	Y	Y	N
MySQL Cluster node ID for this MySQL server
`ndb-mgmd-host`	Y	N
`ndb-mgmd-host`	Y	N	N
Set the host (and port, if desired) for connecting to the management server
`ndb-wait-connected`	Y	Y	Global
`ndb-wait-connected`	Y	N	N
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`	Y	Y	Global
`ndb-wait-setup`	Y	N	N
Time (in seconds) for the MySQL server to wait for NDB engine setup to complete.
`ndbcluster`	Y	N
`ndbcluster`	Y	N	N
Enable NDB Cluster (if this version of MySQL supports it)
`ndbinfo_database`	N	Y	Global
`ndbinfo_database`	N	N	N
The name used for the NDB information database; read only.
`ndbinfo_max_bytes`	Y	Y	Both
`ndbinfo_max_bytes`	N	N	Y
Used for debugging only.
`ndbinfo_max_rows`	Y	Y	Both
`ndbinfo_max_rows`	N	N	Y
Used for debugging only.
`ndbinfo_show_hidden`	Y	Y	Both
`ndbinfo_show_hidden`	N	N	Y
Whether to show ndbinfo internal base tables in the mysql client. The default is OFF.
`ndbinfo_table_prefix`	Y	Y	Both
`ndbinfo_table_prefix`	N	N	Y
The prefix to use for naming ndbinfo internal base tables. Defaults to 'ndb$'.
`ndbinfo_version`	N	Y	Global
`ndbinfo_version`	N	N	N
The version of the ndbinfo engine; read only.
`server-id-bits`	Y	Y	Global
`server-id-bits`	Y	N	N
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.
`transaction_allow_batching`	N	Y	Session
`transaction_allow_batching`	N	N	Y
Allows batching of statements within a transaction. Disable AUTOCOMMIT to use.
`have_ndbcluster`	N	Y	Global
`have_ndbcluster`	N	N	N
Whether mysqld supports NDB Cluster tables (set by --ndbcluster option)
`ndb-deferred-constraints`	Y	Y	Both
`ndb-deferred-constraints`	Y	N	Y
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_deferred_constraints`	Y	Y	Both
`ndb_deferred_constraints`	Y	N	Y
Specifies that constraint checks should be deferred (where these are supported). Not normally needed or used; for testing purposes only.
`ndb-distribution`	Y	Y	Both
`ndb-distribution`	Y	N	Y
Default distribution for new tables in NDBCLUSTER (KEYHASH or LINHASH, default is KEYHASH)
`ndb_distribution`	Y	Y	Both
`ndb_distribution`	Y	N	Y
Default distribution for new tables in NDBCLUSTER (KEYHASH or LINHASH, default is KEYHASH)
`ndb_optimized_node_selection`	Y	N
`ndb_optimized_node_selection`	Y	N	N
Determines how an SQL node chooses a cluster data node to use as transaction coordinator
`ndb_report_thresh_binlog_epoch_slip`	Y	N
`ndb_report_thresh_binlog_epoch_slip`	Y	N	N
This is a threshold on the number of epochs to be behind before reporting binlog status
`ndb_report_thresh_binlog_mem_usage`	Y	N
`ndb_report_thresh_binlog_mem_usage`	Y	N	N
This is a threshold on the percentage of free memory remaining before reporting binlog status
`ndb_use_transactions`	Y	Y	Both
`ndb_use_transactions`	Y	N	Y
Forces NDB to use a count of records during SELECT COUNT(*) query planning to speed up this type of query
`Ndb_cluster_node_id`	N	N	Both
`Ndb_cluster_node_id`	N	Y	N
If the server is acting as a MySQL Cluster node, then the value of this variable its node ID in the cluster
`Ndb_config_from_host`	N	N	Both
`Ndb_config_from_host`	N	Y	N
The host name or IP address of the Cluster management server. Formerly Ndb_connected_host
`Ndb_config_from_port`	N	N	Both
`Ndb_config_from_port`	N	Y	N
The port for connecting to the Cluster management server. Formerly Ndb_connected_port
`Com_show_ndb_status`	N	N	Both
`Com_show_ndb_status`	N	Y	N
Count of SHOW NDB STATUS statements