ndbinfo：NDB群集信息数据库
ndbinfo是一个数据库，其中包含特定于NDB Cluster的信息。
该数据库包含许多表，每个表提供有关NDB群集节点状态，资源使用情况和操作的不同类型的数据。在接下来的几节中，您将找到有关这些表的更多详细信息。
ndbinfo包含在MySQL服务器的NDB群集支持中；不需要特殊的编译或配置步骤；这些表是由MySQL服务器连接到群集时创建的。您可以ndbinfo使用SHOW PLUGINS；在给定的MySQL Server实例中验证支持是否处于活动状态。如果ndbinfo启用了支持，则应该ndbinfo在该Name列和ACTIVE该Status列中看到一行，如下所示（强调的文本）：
mysql>SHOW PLUGINS ; +---------------------------------- +-------- +-------------------- +--------- +--------- + | Name | Status | Type | Library | License | +---------------------------------- +-------- +-------------------- +--------- +--------- + | binlog | ACTIVE | STORAGE ENGINE | NULL | GPL | | mysql_native_password | ACTIVE | AUTHENTICATION | NULL | GPL | | sha256_password | ACTIVE | AUTHENTICATION | NULL | GPL | | MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL | | MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL | | CSV | ACTIVE | STORAGE ENGINE | NULL | GPL | | MyISAM | ACTIVE | STORAGE ENGINE | NULL | GPL | | InnoDB | ACTIVE | STORAGE ENGINE | NULL | GPL | | INNODB_TRX | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_LOCKS | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_LOCK_WAITS | 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_SYS_TABLES | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_TABLESTATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_INDEXES | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_COLUMNS | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_FIELDS | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_FOREIGN | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_FOREIGN_COLS | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_TABLESPACES | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_DATAFILES | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | INNODB_SYS_VIRTUAL | ACTIVE | INFORMATION SCHEMA | NULL | GPL | | PERFORMANCE_SCHEMA | 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 | | BLACKHOLE | ACTIVE | STORAGE ENGINE | NULL | GPL | | ARCHIVE | ACTIVE | STORAGE ENGINE | NULL | GPL | | partition | ACTIVE | STORAGE ENGINE | NULL | GPL | | ngram | ACTIVE | FTPARSER | NULL | GPL | +---------------------------------- +-------- +-------------------- +--------- +--------- + 46 rows in set (0.00 sec)
您也可以通过检查SHOW ENGINES包含ndbinfo在Engine列和列YES中的行的输出来执行此操作Support，如下所示（强调的文本）：
mysql>SHOW ENGINES \G *************************** 1. row*************************** Engine: ndbcluster Support: YES Comment: Clustered, fault-tolerant tables Transactions: YES XA: NO Savepoints: NO *************************** 2. row*************************** Engine: CSV Support: YES Comment: CSV storage engine Transactions: NO XA: NO Savepoints: NO *************************** 3. row*************************** Engine: InnoDB Support: DEFAULT Comment: Supports transactions, row-level locking, and foreign keys Transactions: YES XA: YES Savepoints: YES *************************** 4. row*************************** Engine: BLACKHOLE Support: YES Comment: /dev/null storage engine (anything you write to it disappears) Transactions: NO XA: NO Savepoints: NO *************************** 5. row*************************** Engine: MyISAM Support: YES Comment: MyISAM storage engine Transactions: NO XA: NO Savepoints: NO *************************** 6. row*************************** Engine: MRG_MYISAM Support: YES Comment: Collection of identical MyISAM tables Transactions: NO XA: NO Savepoints: NO *************************** 7. row*************************** Engine: ARCHIVE Support: YES Comment: Archive storage engine Transactions: NO XA: NO Savepoints: NO *************************** 8. row*************************** Engine: ndbinfo Support: YES Comment: NDB Cluster system information storage engine Transactions: NO XA: NO Savepoints: NO *************************** 9. row*************************** Engine: PERFORMANCE_SCHEMA Support: YES Comment: Performance Schema Transactions: NO XA: NO Savepoints: NO *************************** 10. row*************************** Engine: MEMORY Support: YES Comment: Hash based, stored in memory, useful for temporary tables Transactions: NO XA: NO Savepoints: NO 10 rows in set (0.00 sec)
如果ndbinfo启用了支持，则可以ndbinfo在mysql或另一个MySQL客户端中使用SQL语句进行访问。例如，您可以ndbinfo在的输出中看到列出的内容SHOW DATABASES，如下所示（强调的文字）：
mysql>SHOW DATABASES ; +-------------------- + | Database | +-------------------- + | information_schema | | mysql | | ndbinfo | | performance_schema | | sys | +-------------------- + 5 rows in set (0.04 sec)
如果mysqld进程不是使用该--ndbcluster选项启动的，则该进程ndbinfo不可用，也不显示SHOW DATABASES。如果mysqld以前已连接到NDB群集，但是该群集不可用（由于群集关闭，网络连接丢失等事件），ndbinfo并且其表仍然可见，但是尝试访问任何表（不是blocks或config_params）失败，并从NDBINFO获得错误157'到NDB的连接失败'。
除了blocks和config_params表，我们所谓的ndbinfo“表”实际上是从内部NDB表生成的视图，这些内部表通常是MySQL Server不可见的。
所有ndbinfo表都是只读的，在查询时按需生成。由于它们中的许多是由数据节点并行生成的，而另一些则特定于给定的SQL节点，因此不能保证它们提供一致的快照。
此外，ndbinfo表不支持下推连接；因此ndbinfo，即使查询使用WHERE子句，联接大表也可能需要将大量数据传输到发出请求的API节点。
ndbinfo表不包括在查询缓存中。（缺陷＃59831）
您可以ndbinfo使用一条USE语句选择数据库，然后发出一条SHOW TABLES语句以获取表列表，就像其他任何数据库一样，如下所示：
mysql>USE ndbinfo;Database changed mysql>SHOW TABLES ; +--------------------------------- + | Tables_in_ndbinfo | +--------------------------------- + | arbitrator_validity_detail | | arbitrator_validity_summary | | blocks | | cluster_locks | | cluster_operations | | cluster_transactions | | config_nodes | | config_params | | config_values | | counters | | cpustat | | cpustat_1sec | | cpustat_20sec | | cpustat_50ms | | dict_obj_info | | dict_obj_types | | disk_write_speed_aggregate | | disk_write_speed_aggregate_node | | disk_write_speed_base | | diskpagebuffer | | error_messages | | locks_per_fragment | | logbuffers | | logspaces | | membership | | memory_per_fragment | | memoryusage | | nodes | | operations_per_fragment | | 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 | | transporters | +--------------------------------- + 44 rows in set (0.00 sec)
在NDB 8.0中，所有ndbinfo表都使用NDB存储引擎。但是，ndbinfo条目仍然出现在和的输出中SHOW ENGINES，SHOW PLUGINS如前所述。
您可以SELECT像通常期望的那样对这些表执行语句：
mysql>SELECT *FROM memoryusage; +--------- +--------------------- +-------- +------------ +------------ +------------- + | node_id | memory_type | used | used_pages | total | total_pages | +--------- +--------------------- +-------- +------------ +------------ +------------- + | 5 | Data memory | 753664 | 23 | 1073741824 | 32768 | | 5 | Index memory | 163840 | 20 | 1074003968 | 131104 | | 5 | Long message buffer | 2304 | 9 | 67108864 | 262144 | | 6 | Data memory | 753664 | 23 | 1073741824 | 32768 | | 6 | Index memory | 163840 | 20 | 1074003968 | 131104 | | 6 | Long message buffer | 2304 | 9 | 67108864 | 262144 | +--------- +--------------------- +-------- +------------ +------------ +------------- + 6 rows in set (0.02 sec)
可以进行更复杂的查询，例如SELECT使用该memoryusage表的以下两个语句：
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 (0.37 sec) mysql>SELECT SUM(max)as 'Total IndexMemory Available' >FROM memoryusage >WHERE memory_type = 'Index memory'; +----------------------------- + | Total IndexMemory Available | +----------------------------- + | 25664 | +----------------------------- + 1 row in set (0.33 sec)
ndbinfo表和列的名称区分大小写（ndbinfo数据库本身的名称也是如此）。这些标识符是小写的。尝试使用错误的字母大写会导致错误，如以下示例所示：
mysql>SELECT *FROM nodes; +--------- +-------- +--------- +------------- + | node_id | uptime | status | start_phase | +--------- +-------- +--------- +------------- + | 1 | 13602 | STARTED | 0 | | 2 | 16 | STARTED | 0 | +--------- +-------- +--------- +------------- + 2 rows in set (0.04 sec) mysql>SELECT *FROM Nodes; ERROR 1146 (42S02): Table 'ndbinfo.Nodes' doesn't exist
mysqldumpndbinfo完全忽略数据库，并将其从任何输出中排除。即使使用--databases或--all-databases选项，也是如此。
NDB Cluster还维护INFORMATION_SCHEMA信息数据库中的FILES表，其中包括包含有关用于NDB Cluster磁盘数据存储的文件的信息的ndb_transid_mysql_connection_map表，以及显示事务，事务协调器和NDB Cluster API节点之间关系的表。有关更多信息，请参见表的描述或“ NDB群集的INFORMATION_SCHEMA表”。