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
- CreatePolicyStmt
- PolicyName
- PlacementOptionList
- PlacementOption
- CommonPlacementOption
- SugarPlacementOption
- AdvancedPlacementOption
CreatePolicyStmt ::=
"CREATE" "PLACEMENT" "POLICY" IfNotExists PolicyName PlacementOptionList
PolicyName ::=
Identifier
PlacementOptionList ::=
PlacementOption
| PlacementOptionList PlacementOption
| PlacementOptionList ',' PlacementOption
PlacementOption ::=
CommonPlacementOption
| SugarPlacementOption
| AdvancedPlacementOption
CommonPlacementOption ::=
"FOLLOWERS" EqOpt LengthNum
SugarPlacementOption ::=
"PRIMARY_REGION" EqOpt stringLit
| "REGIONS" EqOpt stringLit
| "SCHEDULE" EqOpt stringLit
AdvancedPlacementOption ::=
"LEARNERS" EqOpt LengthNum
| "CONSTRAINTS" EqOpt stringLit
| "LEADER_CONSTRAINTS" EqOpt stringLit
| "FOLLOWER_CONSTRAINTS" EqOpt stringLit
| "LEARNER_CONSTRAINTS" EqOpt stringLit
| "SURVIVAL_PREFERENCES" EqOpt stringLit
示例
CREATE PLACEMENT POLICY p1 PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4;
CREATE TABLE t1 (a INT) PLACEMENT POLICY=p1;
SHOW CREATE PLACEMENT POLICY p1;
Query OK, 0 rows affected (0.08 sec)
Query OK, 0 rows affected (0.10 sec)
+--------+---------------------------------------------------------------------------------------------------+
| Policy | Create Policy |
+--------+---------------------------------------------------------------------------------------------------+
| p1 | CREATE PLACEMENT POLICY `p1` PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 |
+--------+---------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
MySQL 兼容性
该语句是 TiDB 对 MySQL 语法的扩展。