CREATE PLACEMENT POLICY

CREATE PLACEMENT POLICY 用于创建命名的放置策略，随后可以将该策略分配给表、分区或数据库。

语法图

  1. CreatePolicyStmt ::=
  2.     "CREATE" "PLACEMENT" "POLICY" IfNotExists PolicyName PlacementOptionList
  4. PolicyName ::=
  5.     Identifier
  7. PlacementOptionList ::=
  8.     PlacementOption
  9. |   PlacementOptionList PlacementOption
  10. |   PlacementOptionList ',' PlacementOption
  12. PlacementOption ::=
  13.     CommonPlacementOption
  14. |   SugarPlacementOption
  15. |   AdvancedPlacementOption
  17. CommonPlacementOption ::=
  18.     "FOLLOWERS" EqOpt LengthNum
  20. SugarPlacementOption ::=
  21.     "PRIMARY_REGION" EqOpt stringLit
  22. |   "REGIONS" EqOpt stringLit
  23. |   "SCHEDULE" EqOpt stringLit
  25. AdvancedPlacementOption ::=
  26.     "LEARNERS" EqOpt LengthNum
  27. |   "CONSTRAINTS" EqOpt stringLit
  28. |   "LEADER_CONSTRAINTS" EqOpt stringLit
  29. |   "FOLLOWER_CONSTRAINTS" EqOpt stringLit
  30. |   "LEARNER_CONSTRAINTS" EqOpt stringLit

示例

注意：

如要查看所在集群中可用的区域，见 SHOW PLACEMENT LABELS。如果未看到任何可用的区域，此 TiKV 集群在部署时可能未正确设置标签 (label)。

  1. CREATE PLACEMENT POLICY p1 PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4;
  2. CREATE TABLE t1 (a INT) PLACEMENT POLICY=p1;
  3. SHOW CREATE PLACEMENT POLICY p1;
  1. Query OK, 0 rows affected (0.08 sec)
  3. Query OK, 0 rows affected (0.10 sec)
  5. +--------+---------------------------------------------------------------------------------------------------+
  6. | Policy | Create Policy                                                                                     |
  7. +--------+---------------------------------------------------------------------------------------------------+
  8. | p1     | CREATE PLACEMENT POLICY `p1` PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 |
  9. +--------+---------------------------------------------------------------------------------------------------+
  10. 1 row in set (0.00 sec)

MySQL 兼容性

该语句是 TiDB 对 MySQL 语法的扩展。

另请参阅