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sql-statement-create-placement-policy.md

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CREATE PLACEMENT POLICY
The usage of CREATE PLACEMENT POLICY in TiDB.

CREATE PLACEMENT POLICY

Warning:

Placement Rules in SQL is an experimental feature. The syntax might change before its GA, and there might also be bugs.

If you understand the risks, you can enable this experiment feature by executing SET GLOBAL tidb_enable_alter_placement = 1;.

CREATE PLACEMENT POLICY is used to create a named placement policy that can later be assigned to tables, partitions, or database schemas.

Synopsis

CreatePolicyStmt ::=
    "CREATE" "PLACEMENT" "POLICY" IfNotExists PolicyName PlacementOptionList

PolicyName ::=
    Identifier

PlacementOptionList ::=
    DirectPlacementOption
|   PlacementOptionList DirectPlacementOption
|   PlacementOptionList ',' DirectPlacementOption

DirectPlacementOption ::=
    "PRIMARY_REGION" EqOpt stringLit
|   "REGIONS" EqOpt stringLit
|   "FOLLOWERS" EqOpt LengthNum
|   "VOTERS" EqOpt LengthNum
|   "LEARNERS" EqOpt LengthNum
|   "SCHEDULE" EqOpt stringLit
|   "CONSTRAINTS" EqOpt stringLit
|   "LEADER_CONSTRAINTS" EqOpt stringLit
|   "FOLLOWER_CONSTRAINTS" EqOpt stringLit
|   "VOTER_CONSTRAINTS" EqOpt stringLit
|   "LEARNER_CONSTRAINTS" EqOpt stringLit

Examples

Note:

To know which regions are available in your cluster, see SHOW PLACEMENT LABELS.

If you do not see any available regions, your TiKV installation might not have labels set correctly.

{{< copyable "sql" >}}

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 compatibility

This statement is a TiDB extension to MySQL syntax.

See also