7.ENGINES

7. ENGINES

ENGINES表提供有关存储引擎的信息。 这对于检查是否支持存储引擎或查看默认引擎是什么特别有用。

INFORMATION_SCHEMA NameSHOW NameENGINEEngineSUPPORTSupportCOMMENTCommentTRANSACTIONSTransactionsXAXASAVEPOINTSSavepoints

ENGINES表有以下列：

ENGINE：存储引擎名称SUPPORT：服务器对存储引擎的支持级别，如下表所示。 值含义YES引擎受支持且处于活动状态DEFAULT类似YES，并且表示是默认引擎NO不支持引擎DISABLED引擎受支持但已被禁用

值NO表示编译服务器时不支持引擎，因此无法在运行时启用它。

出现DISABLED值的原因是服务器是使用禁用引擎的选项启动的，或者因为没有给出启用它所需的所有选项。 在后一种情况下，错误日志应包含指示禁用该选项的原因。 请参见第“错误日志”。

如果服务器已编译为支持存储引擎，您可能还会看到DISABLED，但是使用--skip-engine_name选项启动。 对于NDB存储引擎，DISABLED表示服务器是在支持NDB Cluster的情况下编译的，但未使用--ndbcluster选项启动。

所有MySQL服务器都支持MyISAM表。 无法禁用MyISAM。

COMMENT：存储引擎的简要说明。TRANSACTIONS：存储引擎是否支持XA事务。SAVEPOINTS：存储引擎是否支持保存点。

该ENGINES表是一个非标准INFORMATION_SCHEMA表。

mysql> select * from information_schema.engines; +--------------------+---------+----------------------------------------------------------------+--------------+------+------------+ | ENGINE | SUPPORT | COMMENT | TRANSACTIONS | XA | SAVEPOINTS | +--------------------+---------+----------------------------------------------------------------+--------------+------+------------+ | CSV | YES | CSV storage engine | NO | NO | NO | | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO | | MyISAM | YES | MyISAM storage engine | NO | NO | NO | | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | | ARCHIVE | YES | Archive storage engine | NO | NO | NO | | InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES | | FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL | +--------------------+---------+----------------------------------------------------------------+--------------+------+------------+ 9 rows in set (0.00 sec) mysql> show engines; +--------------------+---------+----------------------------------------------------------------+--------------+------+------------+ | Engine | Support | Comment | Transactions | XA | Savepoints | +--------------------+---------+----------------------------------------------------------------+--------------+------+------------+ | CSV | YES | CSV storage engine | NO | NO | NO | | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO | | MyISAM | YES | MyISAM storage engine | NO | NO | NO | | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | | ARCHIVE | YES | Archive storage engine | NO | NO | NO | | InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES | | FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL | +--------------------+---------+----------------------------------------------------------------+--------------+------+------------+ 9 rows in set (0.01 sec)

转载于:https://www.cnblogs.com/wanbin/p/9514643.html