Chapter 22 MySQL NDB Cluster 8.0

Temporary tables.  Temporary tables are not supported. Trying either to create a temporary table that uses the NDB storage engine or to alter an existing temporary table to use NDB fails with the error Table storage engine 'ndbcluster' does not support the create option 'TEMPORARY'.

Indexes and keys in NDB tables.  Keys and indexes on NDB Cluster tables are subject to the following limitations:

Restrictions on foreign keys.  Support for foreign key constraints in NDB 8.0 is comparable to that provided by InnoDB, subject to the following restrictions:

For more information, see Section 13.1.20.6, “Using FOREIGN KEY Constraints”, and Section 1.8.3.2, “FOREIGN KEY Constraints”.

NDB Cluster and geometry data types.  Geometry data types (WKT and WKB) are supported for NDB tables. However, spatial indexes are not supported.

Character sets and binary log files.  Currently, the ndb_apply_status and ndb_binlog_index tables are created using the latin1 (ASCII) character set. Because names of binary logs are recorded in this table, binary log files named using non-Latin characters are not referenced correctly in these tables. This is a known issue, which we are working to fix. (Bug #50226)

To work around this problem, use only Latin-1 characters when naming binary log files or setting any the --basedir, --log-bin, or --log-bin-index options.

Creating NDB tables with user-defined partitioning.  Support for user-defined partitioning in NDB Cluster is restricted to [LINEAR] KEY partitioning. Using any other partitioning type with ENGINE=NDB or ENGINE=NDBCLUSTER in a CREATE TABLE statement results in an error.

It is possible to override this restriction, but doing so is not supported for use in production settings. For details, see User-defined partitioning and the NDB storage engine (NDB Cluster).

Default partitioning scheme.  All NDB Cluster tables are by default partitioned by KEY using the table's primary key as the partitioning key. If no primary key is explicitly set for the table, the “hidden” primary key automatically created by the NDB storage engine is used instead. For additional discussion of these and related issues, see Section 23.2.5, “KEY Partitioning”.

CREATE TABLE and ALTER TABLE statements that would cause a user-partitioned NDBCLUSTER table not to meet either or both of the following two requirements are not permitted, and fail with an error:

Exception.  If a user-partitioned NDBCLUSTER table is created using an empty column-list (that is, using PARTITION BY [LINEAR] KEY()), then no explicit primary key is required.

Maximum number of partitions for NDBCLUSTER tables.  The maximum number of partitions that can defined for a NDBCLUSTER table when employing user-defined partitioning is 8 per node group. (See Section 22.1.2, “NDB Cluster Nodes, Node Groups, Replicas, and Partitions”, for more information about NDB Cluster node groups.

DROP PARTITION not supported.  It is not possible to drop partitions from NDB tables using ALTER TABLE ... DROP PARTITION. The other partitioning extensions to ALTER TABLE—ADD PARTITION, REORGANIZE PARTITION, and COALESCE PARTITION—are supported for NDB tables, but use copying and so are not optimized. See Section 23.3.1, “Management of RANGE and LIST Partitions” and Section 13.1.9, “ALTER TABLE Syntax”.

Row-based replication.  When using row-based replication with NDB Cluster, binary logging cannot be disabled. That is, the NDB storage engine ignores the value of sql_log_bin.

JSON data type.  The MySQL JSON data type is supported for NDB tables in the mysqld supplied with NDB 8.0.

An NDB table can have a maximum of 3 JSON columns.

The NDB API has no special provision for working with JSON data, which it views simply as BLOB data. Handling data as JSON must be performed by the application.

A DELETE statement on an NDB table makes the memory formerly used by the deleted rows available for re-use by inserts on the same table only. However, this memory can be made available for general re-use by performing OPTIMIZE TABLE.

A rolling restart of the cluster also frees any memory used by deleted rows. See Section 22.5.5, “Performing a Rolling Restart of an NDB Cluster”.

A DROP TABLE or TRUNCATE TABLE operation on an NDB table frees the memory that was used by this table for re-use by any NDB table, either by the same table or by another NDB table.

Limits imposed by the cluster's configuration.  A number of hard limits exist which are configurable, but available main memory in the cluster sets limits. See the complete list of configuration parameters in Section 22.3.3, “NDB Cluster Configuration Files”. Most configuration parameters can be upgraded online. These hard limits include:

Node and data object maximums.  The following limits apply to numbers of cluster nodes and metadata objects:

See Previous NDB Cluster Issues Resolved in NDB Cluster 7.3, for more information.

Transaction isolation level.  The NDBCLUSTER storage engine supports only the READ COMMITTED transaction isolation level. (InnoDB, for example, supports READ COMMITTED, READ UNCOMMITTED, REPEATABLE READ, and SERIALIZABLE.) You should keep in mind that NDB implements READ COMMITTED on a per-row basis; when a read request arrives at the data node storing the row, what is returned is the last committed version of the row at that time.

Uncommitted data is never returned, but when a transaction modifying a number of rows commits concurrently with a transaction reading the same rows, the transaction performing the read can observe “before” values, “after” values, or both, for different rows among these, due to the fact that a given row read request can be processed either before or after the commit of the other transaction.

To ensure that a given transaction reads only before or after values, you can impose row locks using SELECT ... LOCK IN SHARE MODE. In such cases, the lock is held until the owning transaction is committed. Using row locks can also cause the following issues:

NDB uses READ COMMITTED for all reads unless a modifier such as LOCK IN SHARE MODE or FOR UPDATE is used. LOCK IN SHARE MODE causes shared row locks to be used; FOR UPDATE causes exclusive row locks to be used. Unique key reads have their locks upgraded automatically by NDB to ensure a self-consistent read; BLOB reads also employ extra locking for consistency.

See Section 22.5.3.4, “NDB Cluster Backup Troubleshooting”, for information on how NDB Cluster's implementation of transaction isolation level can affect backup and restoration of NDB databases.

Transactions and BLOB or TEXT columns.  NDBCLUSTER stores only part of a column value that uses any of MySQL's BLOB or TEXT data types in the table visible to MySQL; the remainder of the BLOB or TEXT is stored in a separate internal table that is not accessible to MySQL. This gives rise to two related issues of which you should be aware whenever executing SELECT statements on tables that contain columns of these types:

Rollbacks.  There are no partial transactions, and no partial rollbacks of transactions. A duplicate key or similar error causes the entire transaction to be rolled back.

This behavior differs from that of other transactional storage engines such as InnoDB that may roll back individual statements.

Transactions and memory usage.  As noted elsewhere in this chapter, NDB Cluster does not handle large transactions well; it is better to perform a number of small transactions with a few operations each than to attempt a single large transaction containing a great many operations. Among other considerations, large transactions require very large amounts of memory. Because of this, the transactional behavior of a number of MySQL statements is affected as described in the following list:

Transactions and the COUNT() function.  When using NDB Cluster Replication, it is not possible to guarantee the transactional consistency of the COUNT() function on the slave. In other words, when performing on the master a series of statements (INSERT, DELETE, or both) that changes the number of rows in a table within a single transaction, executing SELECT COUNT(*) FROM table queries on the slave may yield intermediate results. This is due to the fact that SELECT COUNT(...) may perform dirty reads, and is not a bug in the NDB storage engine. (See Bug #31321 for more information.)

Temporary errors.  When first starting a node, it is possible that you may see Error 1204 Temporary failure, distribution changed and similar temporary errors.

Errors due to node failure.  The stopping or failure of any data node can result in a number of different node failure errors. (However, there should be no aborted transactions when performing a planned shutdown of the cluster.)

Database and table names.  When using the NDB storage engine, the maximum allowed length both for database names and for table names is 63 characters. A statement using a database name or table name longer than this limit fails with an appropriate error.

Number of database objects.  The maximum number of all NDB database objects in a single NDB Cluster—including databases, tables, and indexes—is limited to 20320.

Attributes per table.  The maximum number of attributes (that is, columns and indexes) that can belong to a given table is 512.

Attributes per key.  The maximum number of attributes per key is 32.

Row size.  The maximum permitted size of any one row is 14000 bytes. Each BLOB or TEXT column contributes 256 + 8 = 264 bytes to this total.

BIT column storage per table.  The maximum combined width for all BIT columns used in a given NDB table is 4096.

FIXED column storage.  NDB Cluster 8.0 supports a maximum of 128 TB per fragment of data in FIXED columns.

Index prefixes.  Prefixes on indexes are not supported for NDB tables. If a prefix is used as part of an index specification in a statement such as CREATE TABLE, ALTER TABLE, or CREATE INDEX, the prefix is not created by NDB.

A statement containing an index prefix, and creating or modifying an NDB table, must still be syntactically valid. For example, the following statement always fails with Error 1089 Incorrect prefix key; the used key part isn't a string, the used length is longer than the key part, or the storage engine doesn't support unique prefix keys, regardless of storage engine:

CREATE TABLE t1 (
    c1 INT NOT NULL,
    c2 VARCHAR(100),
    INDEX i1 (c2(500))
);

This happens on account of the SQL syntax rule that no index may have a prefix larger than itself.

Savepoints and rollbacks.  Savepoints and rollbacks to savepoints are ignored as in MyISAM.

Durability of commits.  There are no durable commits on disk. Commits are replicated, but there is no guarantee that logs are flushed to disk on commit.

Replication.  Statement-based replication is not supported. Use --binlog-format=ROW (or --binlog-format=MIXED) when setting up cluster replication. See Section 22.6, “NDB Cluster Replication”, for more information.

Replication using global transaction identifiers (GTIDs) is not compatible with NDB Cluster, and is not supported in NDB Cluster 8.0. Do not enable GTIDs when using the NDB storage engine, as this is very likely to cause problems up to and including failure of NDB Cluster Replication.

Semisynchronous replication is not supported in NDB Cluster.

Generated columns.  The NDB storage engine does not support indexes on virtual generated columns.

As with other storage engines, you can create an index on a stored generated column, but you should bear in mind that NDB uses DataMemory for storage of the generated column as well as IndexMemory for the index. See JSON columns and indirect indexing in NDB Cluster, for an example.

NDB Cluster writes changes in stored generated columns to the binary log, but does log not those made to virtual columns. This should not effect NDB Cluster Replication or replication between NDB and other MySQL storage engines.

Range scans.  There are query performance issues due to sequential access to the NDB storage engine; it is also relatively more expensive to do many range scans than it is with either MyISAM or InnoDB.

Reliability of Records in range.  The Records in range statistic is available but is not completely tested or officially supported. This may result in nonoptimal query plans in some cases. If necessary, you can employ USE INDEX or FORCE INDEX to alter the execution plan. See Section 8.9.4, “Index Hints”, for more information on how to do this.

Unique hash indexes.  Unique hash indexes created with USING HASH cannot be used for accessing a table if NULL is given as part of the key.

Machine architecture.  All machines used in the cluster must have the same architecture. That is, all machines hosting nodes must be either big-endian or little-endian, and you cannot use a mixture of both. For example, you cannot have a management node running on a PowerPC which directs a data node that is running on an x86 machine. This restriction does not apply to machines simply running mysql or other clients that may be accessing the cluster's SQL nodes.

Binary logging.  NDB Cluster has the following limitations or restrictions with regard to binary logging:

Schema operations (DDL statements) are rejected while any data node restarts.

Number of replicas.  The number of replicas, as determined by the NoOfReplicas data node configuration parameter, is the number of copies of all data stored by NDB Cluster. Setting this parameter to 1 means there is only a single copy; in this case, no redundancy is provided, and the loss of a data node entails loss of data. To guarantee redundancy, and thus preservation of data even if a data node fails, set this parameter to 2, which is the default and recommended value in production.

Setting NoOfReplicas to a value greater than 2 is possible (to a maximum of 4) but unnecessary to guard against loss of data. In addition, values greater than 2 for this parameter are not supported in production.

Maximum number of tablespaces: 2³² (4294967296)

Maximum number of data files per tablespace: 2¹⁶ (65536)

The minimum and maximum possible sizes of extents for tablespace data files are 32K and 2G, respectively. See Section 13.1.21, “CREATE TABLESPACE Syntax”, for more information.

Data files use DataMemory. Usage is the same as for in-memory data.

Data files use file descriptors. It is important to keep in mind that data files are always open, which means the file descriptors are always in use and cannot be re-used for other system tasks.

Extents require sufficient DiskPageBufferMemory; you must reserve enough for this parameter to account for all memory used by all extents (number of extents times size of extents).

No distributed table locks.  A LOCK TABLES works only for the SQL node on which the lock is issued; no other SQL node in the cluster “sees” this lock. This is also true for a lock issued by any statement that locks tables as part of its operations. (See next item for an example.)

ALTER TABLE operations.  ALTER TABLE is not fully locking when running multiple MySQL servers (SQL nodes). (As discussed in the previous item, NDB Cluster does not support distributed table locks.)

If any of the management servers are running on the same host, you must give nodes explicit IDs in connection strings because automatic allocation of node IDs does not work across multiple management servers on the same host. This is not required if every management server resides on a different host.

When a management server starts, it first checks for any other management server in the same NDB Cluster, and upon successful connection to the other management server uses its configuration data. This means that the management server --reload and --initial startup options are ignored unless the management server is the only one running. It also means that, when performing a rolling restart of an NDB Cluster with multiple management nodes, the management server reads its own configuration file if (and only if) it is the only management server running in this NDB Cluster. See Section 22.5.5, “Performing a Rolling Restart of an NDB Cluster”, for more information.

Python 2.6 or higher.  The Auto-Installer requires the Python interpreter and standard libraries. If these are not already installed on the system, you may be able to add them using the system's package manager. Otherwise, you can download them from http://python.org/download/.

Paramiko 2 or higher.  This is required to communicate with remote hosts using SSH. You can download it from http://www.lag.net/paramiko/. Paramiko may also be available from your system's package manager.

Pycrypto version 1.9 or higher.  This cryptography module is required by Paramiko, and can be iunstalled using pip install cryptography. If pip is not installed, and the module is not available using your system's package manage, you can download it from https://www.dlitz.net/software/pycrypto/.

SSH.  A secure shell connection is used to enable the back end to perform actions on remote hosts. For this reason, an SSH server must be running on the remote host. In addition, the system user running the installer must have access to the remote server, either with a user name and password, or by using public and private keys.

HTTPS.  Remote communication between the Web browser front end and the back end is not encrypted by default, which means that information such as the user's SSH password is transmitted in clear text that is readable to anyone. For communication from a remote client to be encrypted, the back end must have a certificate, and the front end must communicate with the back end using HTTPS rather than HTTP. Enabling HTTPS is accomplished most easily through issuing a self-signed certificate. Once the certificate is issued, you must make sure that it is used. You can do this by starting ndb_setup.py from the command line with the --use-https (-S) and --cert-file (-c) options.

A sample certificate file cfg.pem is included and is used by default. This file is located in the mcc directory under the installation share directory; on Linux, the full path to the file is normally /usr/share/mysql/mcc/cfg.pem. On Windows systems, this is usually C:\Program Files\MySQL\MySQL Server 8.0\share\mcc\cfg.pem. Letting the default be used means that, for testing purposes, you can simply start the installer with the -S option to use an HTTPS connection between the browser and the back end.

The Auto-Installer saves the configuration file for a given cluster mycluster01 as mycluster01.mcc in the home directory of the user invoking the ndb_setup.py executable. This file is encrypted with a passphrase supplied by the user (using Fernet); because HTTP transmits the passphrase in the clear, it is strongly recommended that you always use an HTTPS connection to access the Auto-Installer on a remote host.

Certificate-based authentication.  The back end ndb_setup.py process can execute commands on the local host as well as remote hosts. This means that anyone connecting to the back end can take charge of how commands are executed. To reject unwanted connections to the back end, a certificate may be required for authentication of the client. In this case, a certificate must be issued by the user, installed in the browser, and made available to the back end for authentication purposes. You can enact this requirement (together with or in place of password or key authentication) by starting ndb_setup.py with the --ca-certs-file (-a) option.

Welcome: Begin using the Auto-Installer by choosing either to configure a new NDB Cluster, or to continue configuring an existing one.

Define Cluster: Set basic information about the cluster as a whole, such as name, hosts, and load type. Here you can also set the SSH authentication type for accessing remote hosts, if needed.

Define Hosts: Identify the hosts where you intend to run NDB Cluster processes.

Define Processes: Assign one or more processes of a given type or types to each cluster host.

Define Parameters: Set configuration attributes for processes or types of processes.

Deploy Configuration: Deploy the cluster with the configuration set previously; start and stop the deployed cluster.

Automatically save configuration as cookies: Save your configuration information—such as host names, process data, and parameter values—as a cookie in the browser. When this option is chosen, all information except any SSH password is saved. This means that you can quit and restart the browser, and continue working on the same configuration from where you left off at the end of the previous session. This option is enabled by default.

The SSH password is never saved; if you use one, you must supply it at the beginning of each new session.

Show advanced configuration options: Shows by default advanced configuration parameters where available.

Once set, the advanced parameters continue to be used in the configuration file until they are explicitly changed or reset. This is regardless of whether the advanced parameters are currently visible in the installer; in other words, disabling the menu item does not reset the values of any of these parameters.

You can also toggle the display of advanced parameters for individual processes on the Define Parameters screen.

This option is disabled by default.

Automatically get resource information for new hosts: Query new hosts automatically for hardware resource information to pre-populate a number of configuration options and values. In this case, the suggested values are not mandatory, but they are used unless explicitly changed using the appropriate editing options in the installer.

This option is enabled by default.

Contents: Show the built-in user guide. This is opened in a separate browser window, so that it can be used simultaneously with the installer without interrupting workflow.

Current page: Open the built-in user guide to the section describing the page currently displayed in the installer.

About: open a dialog displaying the installer name and the version number of the NDB Cluster distribution with which it was supplied.

For distributions using yum or dnf, you can use the MySQL Yum Repository for NDB Cluster. See Installing MySQL NDB Cluster Using the Yum Repository, for instructions and additional information.

For SLES, you can use the MySQL SLES Repository for NDB Cluster. See Installing MySQL NDB Cluster Using the SLES Repository, for instructions and additional information.

Management node: management-server

Data node: data-node

SQL node: server and common

To build NDB Cluster 8.0, use the MySQL Server 8.0 sources, which you can obtain from https://dev.mysql.com/downloads/.

Formerly, NDB Cluster used its own source code. In MySQL 8.0 and NDB Cluster 8.0, this is no longer the case, and both products are now built from the same source.

You must configure the build using the WITH_NDBCLUSTER option in addition to any other build options you wish to use with CMake. WITH_NDBCLUSTER_STORAGE_ENGINE and WITH_PLUGIN_NDBCLUSTER are supported as aliases for WITH_NDBCLUSTER, and work in exactly the same way.

Arbitration: How arbitration should be performed to avoid split-brain issues in the event of node failure.

ArbitrationTimeout: Maximum time (milliseconds) database partition waits for arbitration signal

BackupDataBufferSize: Default size of databuffer for a backup (in bytes)

BackupDataDir: Path to where to store backups. Note that the string '/BACKUP' is always appended to this setting, so that the *effective* default is FileSystemPath/BACKUP.

BackupDiskWriteSpeedPct: Sets the percentage of the data node's allocated maximum write speed (MaxDiskWriteSpeed) to reserve for LCPs when starting abackup.

BackupLogBufferSize: Default size of log buffer for a backup (in bytes)

BackupMaxWriteSize: Maximum size of file system writes made by backup (in bytes)

BackupMemory: Total memory allocated for backups per node (in bytes)

BackupReportFrequency: Frequency of backup status reports during backup in seconds

BackupWriteSize: Default size of file system writes made by backup (in bytes)

BatchSizePerLocalScan: Used to calculate the number of lock records for scan with hold lock

BuildIndexThreads: Number of threads to use for building ordered indexes during a system or node restart. Also applies when running ndb_restore --rebuild-indexes. Setting this parameter to 0 disables multithreaded building of ordered indexes.

CompressedBackup: Use zlib to compress backups as they are written

CompressedLCP: Write compressed LCPs using zlib

ConnectCheckIntervalDelay: Time between data node connectivity check stages. Data node is considered suspect after 1 interval and dead after 2 intervals with no response.

CrashOnCorruptedTuple: When enabled, forces node to shut down whenever it detects a corrupted tuple.

DataDir: Data directory for this node

DataMemory: Number of bytes on each data node allocated for storing data; subject to available system RAM and size of IndexMemory.

DefaultHashMapSize: Set size (in buckets) to use for table hash maps. Three values are supported: 0, 240, and 3840. Intended primarily for upgrades and downgrades within NDB 7.2.

DictTrace: Enable DBDICT debugging; for NDB development

DiskIOThreadPool: Number of unbound threads for file access (currently only for Disk Data); known as IOThreadPool before MySQL Cluster NDB 6.4.3.

Diskless: Run without using the disk

DiskPageBufferEntries: Number of 32K page entries to allocate in DiskPageBufferMemory. Very large disk transactions may require increasing this value.

DiskPageBufferMemory: Number of bytes on each data node allocated for the disk page buffer cache

DiskSyncSize: Amount of data written to file before a synch is forced

EnablePartialLcp: Enable partial LCP (true); if this disabled (false), all LCPs write full checkpoints.

EnableRedoControl: Enable adaptive checkpointing speed for controlling redo log usage

EventLogBufferSize: Size of circular buffer for NDB log events within data nodes.

ExecuteOnComputer: String referencing an earlier defined COMPUTER

ExtraSendBufferMemory: Memory to use for send buffers in addition to any allocated by TotalSendBufferMemory or SendBufferMemory. Default (0) allows up to 16MB.

FileSystemPath: Path to directory where the data node stores its data (directory must exist)

FileSystemPathDataFiles: Path to directory where the data node stores its Disk Data files. The default value is FilesystemPathDD, if set; otherwise, FilesystemPath is used if it is set; otherwise, the value of DataDir is used.

FileSystemPathDD: Path to directory where the data node stores its Disk Data and undo files. The default value is FileSystemPath, if set; otherwise, the value of DataDir is used.

FileSystemPathUndoFiles: Path to directory where the data node stores its undo files for Disk Data. The default value is FilesystemPathDD, if set; otherwise, FilesystemPath is used if it is set; otherwise, the value of DataDir is used.

FragmentLogFileSize: Size of each redo log file

HeartbeatIntervalDbApi: Time between API node-data node heartbeats. (API connection closed after 3 missed heartbeats)

HeartbeatIntervalDbDb: Time between data node-to-data node heartbeats; data node considered dead after 3 missed heartbeats

HeartbeatOrder: Sets the order in which data nodes check each others' heartbeats for determining whether a given node is still active and connected to the cluster. Must be zero for all data nodes or distinct nonzero values for all data nodes; see documentation for further guidance.

HostName: Host name or IP address for this data node.

IndexMemory: Number of bytes on each data node allocated for storing indexes; subject to available system RAM and size of DataMemory.

IndexStatAutoCreate: Enable/disable automatic statistics collection when indexes are created.

IndexStatAutoUpdate: Monitor indexes for changes and trigger automatic statistics updates

IndexStatSaveScale: Scaling factor used in determining size of stored index statistics.

IndexStatSaveSize: Maximum size in bytes for saved statistics per index.

IndexStatTriggerPct: Threshold percent change in DML operations for index statistics updates. The value is scaled down by IndexStatTriggerScale.

IndexStatTriggerScale: Scale down IndexStatTriggerPct by this amount, multiplied by the base 2 logarithm of the index size, for a large index. Set to 0 to disable scaling.

IndexStatUpdateDelay: Minimum delay between automatic index statistics updates for a given index. 0 means no delay.

InitFragmentLogFiles: Initialize fragment logfiles (sparse/full)

InitialLogFileGroup: Describes a log file group that is created during an initial start. See documentation for format.

InitialNoOfOpenFiles: Initial number of files open per data node. (One thread is created per file)

InitialTablespace: Describes a tablespace that is created during an initial start. See documentation for format.

InsertRecoveryWork: Percentage of RecoveryWork used for inserted rows; has no effect unless partial local checkpoints are in use

LateAlloc: Allocate memory after the connection to the management server has been established.

LcpScanProgressTimeout: Maximum time that local checkpoint fragment scan can be stalled before node is shut down to ensure systemwide LCP progress. Use 0 to disable.

LockExecuteThreadToCPU: A comma-delimited list of CPU IDs

LockMaintThreadsToCPU: CPU ID indicating which CPU runs the maintenance threads

LockPagesInMainMemory: Previously: If set to true/1, then NDB Cluster data is not swapped out to disk. In MySQL 5.0.36/5.1.15 and later: 0=disable locking, 1=lock after memory allocation, 2=lock before memory allocation

LogLevelCheckpoint: Log level of local and global checkpoint information printed to stdout

LogLevelCongestion: Level of congestion information printed to stdout

LogLevelConnection: Level of node connect/disconnect information printed to stdout

LogLevelError: Transporter, heartbeat errors printed to stdout

LogLevelInfo: Heartbeat and log information printed to stdout

LogLevelNodeRestart: Level of node restart and node failure information printed to stdout

LogLevelShutdown: Level of node shutdown information printed to stdout

LogLevelStartup: Level of node startup information printed to stdout

LogLevelStatistic: Level of transaction, operation, and transporter information printed to stdout

LongMessageBuffer: Number of bytes allocated on each data node for internal long messages

MaxAllocate: Maximum size of allocation to use when allocating memory for tables

MaxBufferedEpochs: Allowed numbered of epochs that a subscribing node can lag behind (unprocessed epochs). Exceeding will cause lagging subscribers to be disconnected.

MaxBufferedEpochBytes: Total number of bytes allocated for buffering epochs.

MaxDiskWriteSpeed: Maximum number of bytes per second that can be written by LCP and backup when no restarts are ongoing.

MaxDiskWriteSpeedOtherNodeRestart: Maximum number of bytes per second that can be written by LCP and backup when another node is restarting.

MaxDiskWriteSpeedOwnRestart: Maximum number of bytes per second that can be written by LCP and backup when this node is restarting.

MaxFKBuildBatchSize: Maximum scan batch size to use for building foreign keys. Increasing this value may speed up builds of foreign keys but impacts ongoing traffic as well.

MaxDMLOperationsPerTransaction: Limit size of a transaction; aborts the transaction if it requires more than this many DML operations. Set to 0 to disable.

MaxLCPStartDelay: Time in seconds that LCP polls for checkpoint mutex (to allow other data nodes to complete metadata synchronization), before putting itself in lock queue for parallel recovery of table data.

MaxNoOfAttributes: Suggests a total number of attributes stored in database (sum over all tables)

MaxNoOfConcurrentIndexOperations: Total number of index operations that can execute simultaneously on one data node

MaxNoOfConcurrentOperations: Maximum number of operation records in transaction coordinator

MaxNoOfConcurrentScans: Maximum number of scans executing concurrently on the data node

MaxNoOfConcurrentSubOperations: Maximum number of concurrent subscriber operations

MaxNoOfConcurrentTransactions: Maximum number of transactions executing concurrently on this data node, the total number of transactions that can be executed concurrently is this value times the number of data nodes in the cluster.

MaxNoOfFiredTriggers: Total number of triggers that can fire simultaneously on one data node

MaxNoOfLocalOperations: Maximum number of operation records defined on this data node

MaxNoOfLocalScans: Maximum number of fragment scans in parallel on this data node

MaxNoOfOpenFiles: Maximum number of files open per data node.(One thread is created per file)

MaxNoOfOrderedIndexes: Total number of ordered indexes that can be defined in the system

MaxNoOfSavedMessages: Maximum number of error messages to write in error log and maximum number of trace files to retain

MaxNoOfSubscribers: Maximum number of subscribers (default 0 = MaxNoOfTables * 2)

MaxNoOfSubscriptions: Maximum number of subscriptions (default 0 = MaxNoOfTables)

MaxNoOfTables: Suggests a total number of NDB tables stored in the database

MaxNoOfTriggers: Total number of triggers that can be defined in the system

MaxNoOfUniqueHashIndexes: Total number of unique hash indexes that can be defined in the system

MaxParallelCopyInstances: Number of parallel copies during node restarts. Default is 0, which uses number of LDMs on both nodes, to a maximum of 16.

MaxParallelScansPerFragment: Maximum number of parallel scans per fragment. Once this limit is reached, scans are serialized.

MaxReorgBuildBatchSize: Maximum scan batch size to use for reorganization of table partitions. Increasing this value may speed up table partition reorganization but impacts ongoing traffic as well.

MaxStartFailRetries: Maximum retries when data node fails on startup, requires StopOnError = 0. Setting to 0 causes start attempts to continue indefinitely.

MaxUIBuildBatchSize: Maximum scan batch size to use for building unique keys. Increasing this value may speed up builds of unique keys but impacts ongoing traffic as well.

MemReportFrequency: Frequency of memory reports in seconds; 0 = report only when exceeding percentage limits

MinDiskWriteSpeed: Minimum number of bytes per second that can be written by LCP and backup.

MinFreePct: The percentage of memory resources to keep in reserve for restarts.

NodeGroup: Node group to which the data node belongs; used only during initial start of cluster.

NodeId: Number uniquely identifying the data node among all nodes in the cluster.

NoOfDiskPagesToDiskDuringRestartACC: Disk checkpoint speed

NoOfFragmentLogFiles: Number of 16 MB redo log files in each of 4 file sets belonging to the data node

NoOfReplicas: Number of copies of all data in database; recommended value is 2 (default). Values greater than 2 are not supported in production.

Numa: (Linux only; requires libnuma) Controls NUMA support. Setting to 0 permits system to determine use of interleaving by data node process; 1 means that it is determined by data node.

ODirect: Use O_DIRECT file reads and writes when possible.

ODirectSyncFlag: O_DIRECT writes are treated as synchronized writes; ignored when ODirect is not enabled, InitFragmentLogFiles is set to SPARSE, or both.

RealtimeScheduler: When true, data node threads are scheduled as real-time threads. Default is false.

RecoveryWork: Percentage of storage overhead for LCP files: greater value means less work in normal operations, more work during recovery

RedoBuffer: Number bytes on each data node allocated for writing redo logs

RedoOverCommitCounter: When RedoOverCommitLimit has been exceeded this many times, transactions are aborted, and operations are handled as specified by DefaultOperationRedoProblemAction.

RedoOverCommitLimit: Each time that flushing the current redo buffer takes longer than this many seconds, the number of times that this has happened is compared to RedoOverCommitCounter.

RestartOnErrorInsert: Control the type of restart caused by inserting an error (when StopOnError is enabled)

SchedulerExecutionTimer: Number of microseconds to execute in scheduler before sending

SchedulerResponsiveness: Set NDB scheduler response optimization 0-10; higher values provide better response time but lower throughput

SchedulerSpinTimer: Number of microseconds to execute in scheduler before sleeping

ServerPort: Port used to set up transporter for incoming connections from API nodes

SharedGlobalMemory: Total number of bytes on each data node allocated for any use

StartFailRetryDelay: Delay in seconds after start failure prior to retry; requires StopOnError = 0.

StartFailureTimeout: Milliseconds to wait before terminating. (0=Wait forever)

StartNoNodeGroupTimeout: Time to wait for nodes without a nodegroup before trying to start (0=forever)

StartPartialTimeout: Milliseconds to wait before trying to start without all nodes. (0=Wait forever)

StartPartitionedTimeout: Milliseconds to wait before trying to start partitioned. (0=Wait forever)

StartupStatusReportFrequency: Frequency of status reports during startup

StopOnError: When set to 0, the data node automatically restarts and recovers following node failures

StringMemory: Default size of string memory (0 to 100 = % of maximum, 101+ = actual bytes)

TcpBind_INADDR_ANY: Bind IP_ADDR_ANY so that connections can be made from anywhere (for autogenerated connections)

TimeBetweenEpochs: Time between epochs (synchronization used for replication)

TimeBetweenEpochsTimeout: Timeout for time between epochs. Exceeding will cause node shutdown.

TimeBetweenGlobalCheckpoints: Time between doing group commit of transactions to disk

TimeBetweenGlobalCheckpointsTimeout: Minimum timeout for group commit of transactions to disk

TimeBetweenInactiveTransactionAbortCheck: Time between checks for inactive transactions

TimeBetweenLocalCheckpoints: Time between taking snapshots of the database (expressed in base-2 logarithm of bytes)

TimeBetweenWatchDogCheck: Time between execution checks inside a data node

TimeBetweenWatchDogCheckInitial: Time between execution checks inside a data node (early start phases when memory is allocated)

TotalSendBufferMemory: Total memory to use for all transporter send buffers.

TransactionBufferMemory: Dynamic buffer space (in bytes) for key and attribute data allocated for each data node

TransactionDeadlockDetectionTimeout: Time transaction can spend executing within a data node. This is the time that the transaction coordinator waits for each data node participating in the transaction to execute a request. If the data node takes more than this amount of time, the transaction is aborted.

TransactionInactiveTimeout: Milliseconds that the application waits before executing another part of the transaction. This is the time the transaction coordinator waits for the application to execute or send another part (query, statement) of the transaction. If the application takes too much time, then the transaction is aborted. Timeout = 0 means that the application never times out.

TwoPassInitialNodeRestartCopy: Copy data in 2 passes during initial node restart, which enables multithreaded building of ordered indexes for such restarts.

UndoDataBuffer: Number of bytes on each data node allocated for writing data undo logs

UndoIndexBuffer: Number of bytes on each data node allocated for writing index undo logs

MaxNoOfExecutionThreads: For ndbmtd only, specify maximum number of execution threads

NoOfFragmentLogParts: Number of redo log file groups belonging to this data node; value must be an even multiple of 4.

ThreadConfig: Used for configuration of multithreaded data nodes (ndbmtd). Default is an empty string; see documentation for syntax and other information.

ArbitrationDelay: When asked to arbitrate, arbitrator waits this long before voting (milliseconds)

ArbitrationRank: If 0, then management node is not arbitrator. Kernel selects arbitrators in order 1, 2

DataDir: Data directory for this node

ExecuteOnComputer: String referencing an earlier defined COMPUTER

ExtraSendBufferMemory: Memory to use for send buffers in addition to any allocated by TotalSendBufferMemory or SendBufferMemory. Default (0) allows up to 16MB.

HeartbeatIntervalMgmdMgmd: Time between management node-to-management node heartbeats; the connection between management node is considered lost after 3 missed heartbeats.

HeartbeatThreadPriority: Set heartbeat thread policy and priority for management nodes; see manual for allowed values

HostName: Host name or IP address for this management node.

Id: Number identifying the management node (Id). Now deprecated; use NodeId instead.

LogDestination: Where to send log messages: console, system log, or specified log file

NodeId: Number uniquely identifying the management node among all nodes in the cluster.

PortNumber: Port number to send commands to and fetch configuration from management server

PortNumberStats: Port number used to get statistical information from a management server

TotalSendBufferMemory: Total memory to use for all transporter send buffers

wan: Use WAN TCP setting as default

ApiVerbose: Enable NDB API debugging; for NDB development

ArbitrationDelay: When asked to arbitrate, arbitrator waits this many milliseconds before voting

ArbitrationRank: If 0, then API node is not arbitrator. Kernel selects arbitrators in order 1, 2

AutoReconnect: Specifies whether an API node should reconnect fully when disconnected from the cluster

BatchByteSize: The default batch size in bytes

BatchSize: The default batch size in number of records

ConnectBackoffMaxTime: Specifies longest time in milliseconds (~100ms resolution) to allow between connection attempts to any given data node by this API node. Excludes time elapsed while connection attempts are ongoing, which in worst case can take several seconds. Disable by setting to 0. If no data nodes are currently connected to this API node, StartConnectBackoffMaxTime is used instead.

ConnectionMap: Specifies which data nodes to connect

DefaultHashMapSize: Set size (in buckets) to use for table hash maps. Three values are supported: 0, 240, and 3840. Intended primarily for upgrades and downgrades within NDB 7.2.

DefaultOperationRedoProblemAction: How operations are handled in the event that RedoOverCommitCounter is exceeded

ExecuteOnComputer: String referencing an earlier defined COMPUTER

ExtraSendBufferMemory: Memory to use for send buffers in addition to any allocated by TotalSendBufferMemory or SendBufferMemory. Default (0) allows up to 16MB.

HeartbeatThreadPriority: Set heartbeat thread policy and priority for API nodes; see manual for allowed values

HostName: Host name or IP address for this SQL or API node.

Id: Number identifying MySQL server or API node (Id). Now deprecated; use NodeId instead.

MaxScanBatchSize: The maximum collective batch size for one scan

NodeId: Number uniquely identifying the SQL node or API node among all nodes in the cluster.

StartConnectBackoffMaxTime: Same as ConnectBackoffMaxTime except that this parameter is used in its place if no data nodes are connected to this API node.

TotalSendBufferMemory: Total memory to use for all transporter send buffers

wan: Use WAN TCP setting as default

HostName: Host name or IP address of this computer.

Id: A unique identifier for this computer.

Checksum: If checksum is enabled, all signals between nodes are checked for errors

Group: Used for group proximity; smaller value is interpreted as being closer

NodeId1: ID of node (data node, API node, or management node) on one side of the connection

NodeId2: ID of node (data node, API node, or management node) on one side of the connection

NodeIdServer: Set server side of TCP connection

OverloadLimit: When more than this many unsent bytes are in the send buffer, the connection is considered overloaded.

PreSendChecksum: If this parameter and Checksum are both enabled, perform pre-send checksum checks, and check all TCP signals between nodes for errors

Proxy:

ReceiveBufferMemory: Bytes of buffer for signals received by this node

SendBufferMemory: Bytes of TCP buffer for signals sent from this node

SendSignalId: Sends ID in each signal. Used in trace files. Defaults to true in debug builds.

TCP_MAXSEG_SIZE: Value used for TCP_MAXSEG

TCP_RCV_BUF_SIZE: Value used for SO_RCVBUF

TCP_SND_BUF_SIZE: Value used for SO_SNDBUF

TcpBind_INADDR_ANY: Bind InAddrAny instead of host name for server part of connection

Checksum: If checksum is enabled, all signals between nodes are checked for errors

Group:

NodeId1: ID of node (data node, API node, or management node) on one side of the connection

NodeId2: ID of node (data node, API node, or management node) on one side of the connection

NodeIdServer: Set server side of SHM connection

OverloadLimit: When more than this many unsent bytes are in the send buffer, the connection is considered overloaded.

PreSendChecksum: If this parameter and Checksum are both enabled, perform pre-send checksum checks, and check all SHM signals between nodes for errors

SendBufferMemory: Bytes in shared memory buffer for signals sent from this node

SendSignalId: Sends ID in each signal. Used in trace files.

ShmKey: A shared memory key; when set to 1, this is calculated by NDB

ShmSpinTime: When receiving, number of microseconds to spin before sleeping

ShmSize: Size of shared memory segment

Signum: Signal number to be used for signalling

UseShm: Use shared memory connections between nodes

Checksum: If checksum is enabled, all signals between nodes are checked for errors

Group:

Host1SciId0: SCI-node ID for adapter 0 on Host1 (a computer can have two adapters)

Host1SciId1: SCI-node ID for adapter 1 on Host1 (a computer can have two adapters)

Host2SciId0: SCI-node ID for adapter 0 on Host2 (a computer can have two adapters)

Host2SciId1: SCI-node ID for adapter 1 on Host2 (a computer can have two adapters)

NodeId1: ID of node (data node, API node, or management node) on one side of the connection

NodeId2: ID of node (data node, API node, or management node) on one side of the connection

NodeIdServer:

OverloadLimit: When more than this many unsent bytes are in the send buffer, the connection is considered overloaded.

SendLimit: Transporter send buffer contents are sent when this number of bytes is buffered

SendSignalId: Sends ID in each signal. Used in trace files.

SharedBufferSize: Size of shared memory segment

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: 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

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.

[computer]: Defines cluster hosts. This is not required to configure a viable NDB Cluster, but be may used as a convenience when setting up a large cluster. See Section 22.3.3.4, “Defining Computers in an NDB Cluster”, for more information.

[ndbd]: Defines a cluster data node (ndbd process). See Section 22.3.3.6, “Defining NDB Cluster Data Nodes”, for details.

[mysqld]: Defines the cluster's MySQL server nodes (also called SQL or API nodes). For a discussion of SQL node configuration, see Section 22.3.3.7, “Defining SQL and Other API Nodes in an NDB Cluster”.

[mgm] or [ndb_mgmd]: Defines a cluster management server (MGM) node. For information concerning the configuration of management nodes, see Section 22.3.3.5, “Defining an NDB Cluster Management Server”.

[tcp]: Defines a TCP/IP connection between cluster nodes, with TCP/IP being the default connection protocol. Normally, [tcp] or [tcp default] sections are not required to set up an NDB Cluster, as the cluster handles this automatically; however, it may be necessary in some situations to override the defaults provided by the cluster. See Section 22.3.3.10, “NDB Cluster TCP/IP Connections”, for information about available TCP/IP configuration parameters and how to use them. (You may also find Section 22.3.3.11, “NDB Cluster TCP/IP Connections Using Direct Connections” to be of interest in some cases.)

[shm]: Defines shared-memory connections between nodes. In MySQL 8.0, it is enabled by default, but should still be considered experimental. For a discussion of SHM interconnects, see Section 22.3.3.12, “NDB Cluster Shared-Memory Connections”.

[sci]: Defines Scalable Coherent Interface connections between cluster data nodes. Not supported in NDB 8.0.

NDB Cluster software version

Numbers of data nodes and SQL nodes

Hardware

Operating system

Amount of data to be stored

Size and type of load under which the cluster is to operate