sql-statement-show-placement.md

title	summary
SHOW PLACEMENT	TiDB 数据库中 SHOW PLACEMENT 的使用概况。

SHOW PLACEMENT

警告：

Placement Rules in SQL 是 TiDB 在 v5.3.0 中引入的实验特性，其语法在 GA 前可能会发生变化，还可能存在 bug。如果你知晓潜在的风险，可通过执行 SET GLOBAL tidb_enable_alter_placement = 1; 来开启该实验特性。

SHOW PLACEMENT 汇总了直接放置 (direct placement) 和放置策略 (placement policy) 中的所有放置选项，并以规范的形式呈现这些选项信息。

语法图

ShowStmt ::=
    "PLACEMENT"

示例

{{< 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;
CREATE TABLE t2 (a INT) PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4;
SHOW PLACEMENT;

Query OK, 0 rows affected (0.01 sec)

Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

+---------------+----------------------------------------------------------------------+------------------+
| Target        | Placement                                                            | Scheduling_State |
+---------------+----------------------------------------------------------------------+------------------+
| POLICY p1     | PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 | NULL             |
| DATABASE test | PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 | INPROGRESS       |
| TABLE test.t1 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 | INPROGRESS       |
| TABLE test.t2 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 | INPROGRESS       |
+---------------+----------------------------------------------------------------------+------------------+
4 rows 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

• Placement Rules in SQL
• SHOW PLACEMENT FOR
• CREATE PLACEMENT POLICY