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ndbinfo is a database containing information specific to NDB Cluster.

This database contains a number of tables, each providing a different sort of data about NDB Cluster node status, resource usage, and operations. You can find more detailed information about each of these tables in the next several sections.

ndbinfo is included with NDB Cluster support in the MySQL Server; no special compilation or configuration steps are required; the tables are created by the MySQL Server when it connects to the cluster. You can verify thatndbinfo support is active in a given MySQL Server instance usingSHOW PLUGINS; ifndbinfo support is enabled, you should see a row containingndbinfo in theName column andACTIVE in theStatus column, as shown here (emphasized text):

mysql> SHOW PLUGINS;+----------------------------------+----------+--------------------+---------+---------+| Name                             | Status   | Type               | Library | License |+----------------------------------+----------+--------------------+---------+---------+| binlog                           | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || sha256_password                  | ACTIVE   | AUTHENTICATION     | NULL    | GPL     || caching_sha2_password            | ACTIVE   | AUTHENTICATION     | NULL    | GPL     || sha2_cache_cleaner               | ACTIVE   | AUDIT              | NULL    | GPL     || daemon_keyring_proxy_plugin      | ACTIVE   | DAEMON             | NULL    | GPL     || CSV                              | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || MEMORY                           | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || InnoDB                           | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || INNODB_TRX                       | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_CMP                       | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_CMP_RESET                 | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_CMPMEM                    | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_CMPMEM_RESET              | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_CMP_PER_INDEX             | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_CMP_PER_INDEX_RESET       | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_BUFFER_PAGE               | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_BUFFER_PAGE_LRU           | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_BUFFER_POOL_STATS         | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_TEMP_TABLE_INFO           | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_METRICS                   | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_FT_DEFAULT_STOPWORD       | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_FT_DELETED                | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_FT_BEING_DELETED          | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_FT_CONFIG                 | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_FT_INDEX_CACHE            | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_FT_INDEX_TABLE            | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_TABLES                    | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_TABLESTATS                | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_INDEXES                   | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_TABLESPACES               | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_COLUMNS                   | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_VIRTUAL                   | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_CACHED_INDEXES            | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || INNODB_SESSION_TEMP_TABLESPACES  | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || MyISAM                           | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || MRG_MYISAM                       | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || PERFORMANCE_SCHEMA               | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || TempTable                        | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || ARCHIVE                          | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || BLACKHOLE                        | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || ndbcluster                       | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || ndbinfo                          | ACTIVE   | STORAGE ENGINE     | NULL    | GPL     || ndb_transid_mysql_connection_map | ACTIVE   | INFORMATION SCHEMA | NULL    | GPL     || ngram                            | ACTIVE   | FTPARSER           | NULL    | GPL     || mysqlx_cache_cleaner             | ACTIVE   | AUDIT              | NULL    | GPL     || mysqlx                           | ACTIVE   | DAEMON             | NULL    | GPL     |+----------------------------------+----------+--------------------+---------+---------+46 rows in set (0.00 sec)

You can also do this by checking the output ofSHOW ENGINES for a line includingndbinfo in theEngine column andYES in theSupport column, as shown here (emphasized text):

mysql> SHOW ENGINES\G*************************** 1. row ***************************      Engine: MEMORY     Support: YES     Comment: Hash based, stored in memory, useful for temporary tablesTransactions: NO          XA: NO  Savepoints: NO*************************** 2. row ***************************      Engine: InnoDB     Support: DEFAULT     Comment: Supports transactions, row-level locking, and foreign keysTransactions: YES          XA: YES  Savepoints: YES*************************** 3. row ***************************      Engine: PERFORMANCE_SCHEMA     Support: YES     Comment: Performance SchemaTransactions: NO          XA: NO  Savepoints: NO*************************** 4. row ***************************      Engine: MyISAM     Support: YES     Comment: MyISAM storage engineTransactions: NO          XA: NO  Savepoints: NO*************************** 5. row ***************************Engine: ndbinfoSupport: YES     Comment: MySQL Cluster system information storage engineTransactions: NO          XA: NO  Savepoints: NO*************************** 6. row ***************************      Engine: MRG_MYISAM     Support: YES     Comment: Collection of identical MyISAM tablesTransactions: NO          XA: NO  Savepoints: NO*************************** 7. row ***************************      Engine: BLACKHOLE     Support: YES     Comment: /dev/null storage engine (anything you write to it disappears)Transactions: NO          XA: NO  Savepoints: NO*************************** 8. row ***************************      Engine: CSV     Support: YES     Comment: CSV storage engineTransactions: NO          XA: NO  Savepoints: NO*************************** 9. row ***************************      Engine: ARCHIVE     Support: YES     Comment: Archive storage engineTransactions: NO          XA: NO  Savepoints: NO*************************** 10. row ***************************      Engine: ndbcluster     Support: YES     Comment: Clustered, fault-tolerant tablesTransactions: YES          XA: NO  Savepoints: NO10 rows in set (0.01 sec)

Ifndbinfo support is enabled, then you can accessndbinfo using SQL statements inmysql or another MySQL client. For example, you can seendbinfo listed in the output ofSHOW DATABASES, as shown here (emphasized text):

mysql> SHOW DATABASES;+--------------------+| Database           |+--------------------+| information_schema || mysql              || ndbinfo            || performance_schema || sys                |+--------------------+5 rows in set (0.04 sec)

If themysqld process was not started with the--ndbcluster option,ndbinfo is not available and is not displayed bySHOW DATABASES. Ifmysqld was formerly connected to an NDB Cluster but the cluster becomes unavailable (due to events such as cluster shutdown, loss of network connectivity, and so forth),ndbinfo and its tables remain visible, but an attempt to access any tables (other thanblocks orconfig_params) fails withGot error 157 'Connection to NDB failed' from NDBINFO.

With the exception of theblocks andconfig_params tables, what we refer to asndbinfo“tables” are actually views generated from internalNDB tables not normally visible to the MySQL Server. You can make these tables visible by setting thendbinfo_show_hidden system variable toON (or1), but this is normally not necessary.

Allndbinfo tables are read-only, and are generated on demand when queried. Because many of them are generated in parallel by the data nodes while other are specific to a given SQL node, they are not guaranteed to provide a consistent snapshot.

In addition, pushing down of joins is not supported onndbinfo tables; so joining largendbinfo tables can require transfer of a large amount of data to the requesting API node, even when the query makes use of aWHERE clause.

ndbinfo tables are not included in the query cache. (Bug #59831)

You can select thendbinfo database with aUSE statement, and then issue aSHOW TABLES statement to obtain a list of tables, just as for any other database, like this:

mysql> USE ndbinfo;Database changedmysql> SHOW TABLES;+---------------------------------+| Tables_in_ndbinfo               |+---------------------------------+| arbitrator_validity_detail      || arbitrator_validity_summary     || backup_id                       || blobs                           || blocks                          || certificates                    || cluster_locks                   || cluster_operations              || cluster_transactions            || config_nodes                    || config_params                   || config_values                   || counters                        || cpudata                         || cpudata_1sec                    || cpudata_20sec                   || cpudata_50ms                    || cpuinfo                         || cpustat                         || cpustat_1sec                    || cpustat_20sec                   || cpustat_50ms                    || dict_obj_info                   || dict_obj_tree                   || dict_obj_types                  || dictionary_columns              || dictionary_tables               || disk_write_speed_aggregate      || disk_write_speed_aggregate_node || disk_write_speed_base           || diskpagebuffer                  || diskstat                        || diskstats_1sec                  || error_messages                  || events                          || files                           || foreign_keys                    || hash_maps                       || hwinfo                          || index_columns                   || index_stats                     || locks_per_fragment              || logbuffers                      || logspaces                       || membership                      || memory_per_fragment             || memoryusage                     || nodes                           || operations_per_fragment         || pgman_time_track_stats          || processes                       || resources                       || restart_info                    || server_locks                    || server_operations               || server_transactions             || table_distribution_status       || table_fragments                 || table_info                      || table_replicas                  || tc_time_track_stats             || threadblocks                    || threads                         || threadstat                      || transporter_details             || transporters                    |+---------------------------------+66 rows in set (0.00 sec)

Allndbinfo tables use theNDB storage engine; however, anndbinfo entry still appears in the output ofSHOW ENGINES andSHOW PLUGINS as described previously.

You can executeSELECT statements against these tables, just as you would normally expect:

mysql> SELECT * FROM memoryusage;+---------+---------------------+--------+------------+------------+-------------+| node_id | memory_type         | used   | used_pages | total      | total_pages |+---------+---------------------+--------+------------+------------+-------------+|       5 | Data memory         | 425984 |         13 | 2147483648 |       65536 ||       5 | Long message buffer | 393216 |       1536 |   67108864 |      262144 ||       6 | Data memory         | 425984 |         13 | 2147483648 |       65536 ||       6 | Long message buffer | 393216 |       1536 |   67108864 |      262144 ||       7 | Data memory         | 425984 |         13 | 2147483648 |       65536 ||       7 | Long message buffer | 393216 |       1536 |   67108864 |      262144 ||       8 | Data memory         | 425984 |         13 | 2147483648 |       65536 ||       8 | Long message buffer | 393216 |       1536 |   67108864 |      262144 |+---------+---------------------+--------+------------+------------+-------------+8 rows in set (0.09 sec)

More complex queries, such as the two followingSELECT statements using thememoryusage table, are possible:

mysql> SELECT SUM(used) as 'Data Memory Used, All Nodes'     >     FROM memoryusage     >     WHERE memory_type = 'Data memory';+-----------------------------+| Data Memory Used, All Nodes |+-----------------------------+|                        6460 |+-----------------------------+1 row in set (0.09 sec)mysql> SELECT SUM(used) as 'Long Message Buffer, All Nodes'     >     FROM memoryusage     >     WHERE memory_type = 'Long message buffer';+-------------------------------------+| Long Message Buffer Used, All Nodes |+-------------------------------------+|                             1179648 |+-------------------------------------+1 row in set (0.08 sec)

ndbinfo table and column names are case-sensitive (as is the name of thendbinfo database itself). These identifiers are in lowercase. Trying to use the wrong lettercase results in an error, as shown in this example:

mysql> SELECT * FROM nodes;+---------+--------+---------+-------------+-------------------+| node_id | uptime | status  | start_phase | config_generation |+---------+--------+---------+-------------+-------------------+|       5 |  17707 | STARTED |           0 |                 1 ||       6 |  17706 | STARTED |           0 |                 1 ||       7 |  17705 | STARTED |           0 |                 1 ||       8 |  17704 | STARTED |           0 |                 1 |+---------+--------+---------+-------------+-------------------+4 rows in set (0.06 sec)mysql> SELECT * FROM Nodes;ERROR 1146 (42S02): Table 'ndbinfo.Nodes' doesn't exist

mysqldump ignores thendbinfo database entirely, and excludes it from any output. This is true even when using the--databases or--all-databases option.

NDB Cluster also maintains tables in theINFORMATION_SCHEMA information database, including theFILES table which contains information about files used for NDB Cluster Disk Data storage, and thendb_transid_mysql_connection_map table, which shows the relationships between transactions, transaction coordinators, and NDB Cluster API nodes. For more information, see the descriptions of the tables orSection 25.6.18, “INFORMATION_SCHEMA Tables for NDB Cluster”.