This section provides descriptions of mysqld server options relating to NDB Cluster. For information about mysqld options not specific to NDB Cluster, and for general information about the use of options with mysqld, see Server Command Options.
For information about command-line options used with other NDB Cluster processes, see Chapter 5, NDB Cluster Programs.
-
Command-Line Format --ndbcluster[=value]
Disabled by skip-ndbcluster
Type Enumeration Default Value ON
Valid Values OFF
FORCE
The
NDBCLUSTER
storage engine is necessary for using NDB Cluster. If a mysqld binary includes support for theNDBCLUSTER
storage engine, the engine is disabled by default. Use the--ndbcluster
option to enable it. Use--skip-ndbcluster
to explicitly disable the engine.The
--ndbcluster
option is ignored (and theNDB
storage engine is not enabled) if--initialize
is also used. (It is neither necessary nor desirable to use this option together with--initialize
.) --ndb-allow-copying-alter-table=[ON|OFF]
Command-Line Format --ndb-allow-copying-alter-table[={OFF|ON}]
System Variable ndb_allow_copying_alter_table
Scope Global, Session Dynamic Yes SET_VAR
Hint AppliesNo Type Boolean Default Value ON
Let
ALTER TABLE
and other DDL statements use copying operations onNDB
tables. Set toOFF
to keep this from happening; doing so may improve performance of critical applications.--ndb-applier-allow-skip-epoch
Command-Line Format --ndb-applier-allow-skip-epoch
Introduced 8.0.28-ndb-8.0.28 System Variable ndb_applier_allow_skip_epoch
Scope Global Dynamic No SET_VAR
Hint AppliesNo Use together with
--slave-skip-errors
to causeNDB
to ignore skipped epoch transactions. Has no effect when used alone.-
Command-Line Format --ndb-batch-size
System Variable ndb_batch_size
Scope Global, Session Dynamic Yes SET_VAR
Hint AppliesNo Type Integer Default Value 32768
Minimum Value 0
Maximum Value (≥ 8.0.29-ndb-8.0.29) 2147483648
Maximum Value 2147483648
Maximum Value 2147483648
Maximum Value (≤ 8.0.28-ndb-8.0.28) 31536000
Unit bytes This sets the size in bytes that is used for NDB transaction batches.
--ndb-cluster-connection-pool=
#
Command-Line Format --ndb-cluster-connection-pool
System Variable ndb_cluster_connection_pool
System Variable ndb_cluster_connection_pool
Scope Global Scope Global Dynamic No Dynamic No SET_VAR
Hint AppliesNo SET_VAR
Hint AppliesNo Type Integer Default Value 1
Minimum Value 1
Maximum Value 63
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.
ImportantBecause each SQL node using connection pooling occupies multiple API node slots—each slot having its own node ID in the cluster—you must not use a node ID as part of the cluster connection string when starting any mysqld process that employs connection pooling.
Setting a node ID in the connection string when using the
--ndb-cluster-connection-pool
option causes node ID allocation errors when the SQL node attempts to connect to the cluster.--ndb-cluster-connection-pool-nodeids=
list
Command-Line Format --ndb-cluster-connection-pool-nodeids
System Variable ndb_cluster_connection_pool_nodeids
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Set Default Value Specifies a comma-separated list of node IDs for connections to the cluster used by an SQL node. The number of nodes in this list must be the same as the value set for the
--ndb-cluster-connection-pool
option.--ndb-blob-read-batch-bytes=
bytes
Command-Line Format --ndb-blob-read-batch-bytes
System Variable ndb_blob_read_batch_bytes
Scope Global, Session Dynamic Yes SET_VAR
Hint AppliesNo Type Integer Default Value 65536
Minimum Value 0
Maximum Value 4294967295
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 ofBLOB
data to be read within the current transaction, any pendingBLOB
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.NoteIn NDB API applications, you can control
BLOB
write batching with thesetMaxPendingBlobReadBytes()
andgetMaxPendingBlobReadBytes()
methods.--ndb-blob-write-batch-bytes=
bytes
Command-Line Format --ndb-blob-write-batch-bytes
System Variable ndb_blob_write_batch_bytes
Scope Global, Session Dynamic Yes SET_VAR
Hint AppliesNo Type Integer Default Value 65536
Minimum Value 0
Maximum Value 4294967295
Unit 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 ofBLOB
data to be written within the current transaction, any pendingBLOB
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.NoteIn NDB API applications, you can control
BLOB
write batching with thesetMaxPendingBlobWriteBytes()
andgetMaxPendingBlobWriteBytes()
methods.--ndb-connectstring=
connection_string
Command-Line Format --ndb-connectstring
Type String When using the
NDBCLUSTER
storage engine, this option specifies the management server that distributes cluster configuration data. See Section 4.3.3, “NDB Cluster Connection Strings”, for syntax.--ndb-default-column-format=[FIXED|DYNAMIC]
Command-Line Format --ndb-default-column-format={FIXED|DYNAMIC}
System Variable ndb_default_column_format
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Enumeration Default Value FIXED
Valid Values FIXED
DYNAMIC
Sets the default
COLUMN_FORMAT
andROW_FORMAT
for new tables (see CREATE TABLE Statement). The default isFIXED
.--ndb-deferred-constraints=[0|1]
Command-Line Format --ndb-deferred-constraints
System Variable ndb_deferred_constraints
Scope Global, Session Dynamic Yes SET_VAR
Hint AppliesNo Type Integer Default Value 0
Minimum Value 0
Maximum Value 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.
-
Command-Line Format --ndb-schema-dist-timeout=#
Introduced 8.0.17-ndb-8.0.17 System Variable ndb_schema_dist_timeout
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Integer Default Value 120
Minimum Value 5
Maximum Value 1200
Unit seconds Specifies the maximum time in seconds that this mysqld waits for a schema operation to complete before marking it as having timed out.
--ndb-distribution=[KEYHASH|LINHASH]
Command-Line Format --ndb-distribution={KEYHASH|LINHASH}
System Variable ndb_distribution
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Enumeration Default Value KEYHASH
Valid Values LINHASH
KEYHASH
Controls the default distribution method for
NDB
tables. Can be set to either ofKEYHASH
(key hashing) orLINHASH
(linear hashing).KEYHASH
is the default.-
Command-Line Format --ndb-log-apply-status[={OFF|ON}]
System Variable ndb_log_apply_status
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Boolean Default Value OFF
Causes a replica mysqld to log any updates received from its immediate source to the
mysql.ndb_apply_status
table in its own binary log using its own server ID rather than the server ID of the source. In a circular or chain replication setting, this allows such updates to propagate to themysql.ndb_apply_status
tables of any MySQL servers configured as replicas of the current mysqld.In a chain replication setup, using this option allows downstream (replica) clusters to be aware of their positions relative to all of their upstream contributors (sourcess).
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 replication source 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]
Command-Line Format --ndb-log-empty-epochs[={OFF|ON}]
System Variable ndb_log_empty_epochs
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Boolean Default Value OFF
Causes epochs during which there were no changes to be written to the
ndb_apply_status
andndb_binlog_index
tables, even whenlog_replica_updates
orlog_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 inndb_binlog_index
.Because
--ndb-log-empty-epochs=1
causes the size of thendb_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]
Command-Line Format --ndb-log-empty-update[={OFF|ON}]
System Variable ndb_log_empty_update
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Boolean Default Value OFF
Causes updates that produced no changes to be written to the
ndb_apply_status
andndb_binlog_index
tables, even whenlog_replica_updates
orlog_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-exclusive-reads=[0|1]
Command-Line Format --ndb-log-exclusive-reads[={OFF|ON}]
System Variable ndb_log_exclusive_reads
Scope Global, Session Dynamic Yes SET_VAR
Hint AppliesNo Type Boolean Default Value 0
Starting the server with this option causes primary key reads to be logged with exclusive locks, which allows for NDB Cluster Replication conflict detection and resolution based on read conflicts. You can also enable and disable these locks at runtime by setting the value of the
ndb_log_exclusive_reads
system variable to 1 or 0, respectively. 0 (disable locking) is the default.For more information, see Read conflict detection and resolution.
-
Command-Line Format --ndb-log-fail-terminate
Introduced 8.0.21-ndb-8.0.21 System Variable ndb_log_fail_terminate
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Boolean Default Value FALSE
When this option is specified, and complete logging of all found row events is not possible, the mysqld process is terminated.
-
Command-Line Format --ndb-log-orig[={OFF|ON}]
System Variable ndb_log_orig
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Boolean Default Value OFF
Log the originating server ID and epoch in the
ndb_binlog_index
table.NoteThis 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 7.4, “NDB Cluster Replication Schema and Tables”.
--ndb-log-transaction-dependency
Command-Line Format --ndb-log-transaction-dependency={true|false}
Introduced 8.0.33-ndb-8.0.33 System Variable ndb_log_transaction_dependency
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Boolean Default Value false
Causes the
NDB
binary logging thread to calculate transaction dependencies for each transaction which it writes to the binary log. The default value isFALSE
.This option cannot be set at runtime; the corresponding
ndb_log_transaction_dependency
system variable is read-only.-
Command-Line Format --ndb-log-transaction-id[={OFF|ON}]
System Variable ndb_log_transaction_id
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Boolean Default Value OFF
Causes a replica mysqld to write the NDB transaction ID in each row of the binary log. The default value is
FALSE
.--ndb-log-transaction-id
is required to enable NDB Cluster Replication conflict detection and resolution using theNDB$EPOCH_TRANS()
function (see NDB$EPOCH_TRANS()). For more information, see Section 7.12, “NDB Cluster Replication Conflict Resolution”.The deprecated
log_bin_use_v1_row_events
system variable, which defaults toOFF
, must not be set toON
when you use--ndb-log-transaction-id=ON
. -
Command-Line Format --ndb-log-update-as-write[={OFF|ON}]
System Variable ndb_log_update_as_write
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Boolean Default Value ON
Whether updates on the source are written to the binary log as updates (
OFF
) or writes (ON
). When this option is enabled, and both--ndb-log-updated-only
and--ndb-log-update-minimal
are disabled, operations of different types are loǵged as described in the following list:INSERT
: Logged as aWRITE_ROW
event with no before image; the after image is logged with all columns.UPDATE
: Logged as aWRITE_ROW
event with no before image; the after image is logged with all columns.DELETE
: Logged as aDELETE_ROW
event with all columns logged in the before image; the after image is not logged.
This option can be used for NDB Replication conflict resolution in combination with the other two NDB logging options mentioned previously; see ndb_replication Table, for more information.
-
Command-Line Format --ndb-log-updated-only[={OFF|ON}]
System Variable ndb_log_updated_only
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Boolean Default Value ON
Whether mysqld writes updates only (
ON
) or complete rows (OFF
) to the binary log. When this option is enabled, and both--ndb-log-update-as-write
and--ndb-log-update-minimal
are disabled, operations of different types are loǵged as described in the following list:INSERT
: Logged as aWRITE_ROW
event with no before image; the after image is logged with all columns.UPDATE
: Logged as anUPDATE_ROW
event with primary key columns and updated columns present in both the before and after images.DELETE
: Logged as aDELETE_ROW
event with primary key columns incuded in the before image; the after image is not logged.
This option can be used for NDB Replication conflict resolution in combination with the other two NDB logging options mentioned previously; see ndb_replication Table, for more information about how these options interact with one another.
-
Command-Line Format --ndb-log-update-minimal[={OFF|ON}]
System Variable ndb_log_update_minimal
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Boolean Default Value OFF
Log updates in a minimal fashion, by writing only the primary key values in the before image, and only the changed columns in the after image. This may cause compatibility problems if replicating to storage engines other than
NDB
. When this option is enabled, and both--ndb-log-updated-only
and--ndb-log-update-as-write
are disabled, operations of different types are loǵged as described in the following list:INSERT
: Logged as aWRITE_ROW
event with no before image; the after image is logged with all columns.UPDATE
: Logged as anUPDATE_ROW
event with primary key columns in the before image; all columns except primary key columns are logged in the after image.DELETE
: Logged as aDELETE_ROW
event with all columns in the before image; the after image is not logged.
This option can be used for NDB Replication conflict resolution in combination with the other two NDB logging options mentioned previously; see ndb_replication Table, for more information.
-
Command-Line Format --ndb-mgmd-host=host_name[:port_num]
Type String Default Value localhost:1186
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. -
Command-Line Format --ndb-nodeid=#
Status Variable Ndb_cluster_node_id
Scope Global Dynamic No Type Integer Default Value N/A
Minimum Value 1
Maximum Value 255
Maximum Value 63
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 ofconfig.ini
, or there must be an “open”[mysqld]
or[api]
section in the file (that is, a section without aNodeId
orId
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 ofSHOW STATUS
, and ascluster_node_id
in theconnection
row of the output ofSHOW ENGINE NDBCLUSTER STATUS
.For more information about node IDs for NDB Cluster SQL nodes, see Section 4.3.7, “Defining SQL and Other API Nodes in an NDB Cluster”.
-
Command-Line Format --ndbinfo[=value]
(≥ 8.0.13-ndb-8.0.13)Introduced 8.0.13-ndb-8.0.13 Type Enumeration Default Value ON
Valid Values ON
OFF
FORCE
Enables the plugin for the
ndbinfo
information database. By default this is ON wheneverNDBCLUSTER
is enabled. --ndb-optimization-delay=
milliseconds
Command-Line Format --ndb-optimization-delay=#
System Variable ndb_optimization_delay
Scope Global Dynamic Yes SET_VAR
Hint AppliesNo Type Integer Default Value 10
Minimum Value 0
Maximum Value 100000
Unit milliseconds Set the number of milliseconds to wait between sets of rows by
OPTIMIZE TABLE
statements onNDB
tables. The default is 10.--ndb-optimized-node-selection
Command-Line Format --ndb-optimized-node-selection
Enable optimizations for selection of nodes for transactions. Enabled by default; use
--skip-ndb-optimized-node-selection
to disable.--ndb-transid-mysql-connection-map=
state
Command-Line Format --ndb-transid-mysql-connection-map[=state]
Type Enumeration Default Value ON
Valid Values ON
OFF
FORCE
Enables or disables the plugin that handles the
ndb_transid_mysql_connection_map
table in theINFORMATION_SCHEMA
database. Takes one of the valuesON
,OFF
, orFORCE
.ON
(the default) enables the plugin.OFF
disables the plugin, which makesndb_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 ofSHOW PLUGINS
.-
Command-Line Format --ndb-wait-connected=#
System Variable ndb_wait_connected
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Integer Default Value (≥ 8.0.27-ndb-8.0.27) 120
Default Value (≤ 8.0.26-ndb-8.0.26) 30
Default Value 30
Minimum Value 0
Maximum Value 31536000
Unit 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
. -
Command-Line Format --ndb-wait-setup=#
System Variable ndb_wait_setup
Scope Global Dynamic No SET_VAR
Hint AppliesNo Type Integer Default Value (≥ 8.0.27-ndb-8.0.27) 120
Default Value (≤ 8.0.26-ndb-8.0.26) 30
Default Value 30
Default Value 15
Default Value 15
Minimum Value 0
Maximum Value 31536000
Unit 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 treatingNDB
as unavailable. The time is specified in seconds. The default value is30
. -
Command-Line Format --skip-ndbcluster
Disable the
NDBCLUSTER
storage engine. This is the default for binaries that were built withNDBCLUSTER
storage engine support; the server allocates memory and other resources for this storage engine only if the--ndbcluster
option is given explicitly. See Section 4.1, “Quick Test Setup of NDB Cluster”, for an example.