FLUSH TABLES
此语句是为了与 MySQL 兼容而存在。在 TiDB 中没有实际的使用场景。
概要
- FlushStmt
- NoWriteToBinLogAliasOpt
- FlushOption
- LogTypeOpt
- TableOrTables
- TableNameListOpt
- WithReadLockOpt
FlushStmt ::=
'FLUSH' NoWriteToBinLogAliasOpt FlushOption
NoWriteToBinLogAliasOpt ::=
( 'NO_WRITE_TO_BINLOG' | 'LOCAL' )?
FlushOption ::=
'PRIVILEGES'
| 'STATUS'
| 'TIDB' 'PLUGINS' PluginNameList
| 'HOSTS'
| LogTypeOpt 'LOGS'
| TableOrTables TableNameListOpt WithReadLockOpt
LogTypeOpt ::=
( 'BINARY' | 'ENGINE' | 'ERROR' | 'GENERAL' | 'SLOW' )?
TableOrTables ::=
'TABLE'
| 'TABLES'
TableNameListOpt ::=
TableNameList?
WithReadLockOpt ::=
( 'WITH' 'READ' 'LOCK' )?
示例
mysql> FLUSH TABLES;
Query OK, 0 rows affected (0.00 sec)
mysql> FLUSH TABLES WITH READ LOCK;
ERROR 1105 (HY000): FLUSH TABLES WITH READ LOCK is not supported. Please use @@tidb_snapshot
MySQL 兼容性
- TiDB 没有像 MySQL 那样的表缓存概念。因此，
FLUSH TABLES在 TiDB 中会被解析但忽略，以保持兼容性。 - 语句
FLUSH TABLES WITH READ LOCK会产生错误，因为 TiDB 目前不支持锁定表。建议使用 Historical reads 来实现类似功能。