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SHOW PLACEMENT FOR

SHOW PLACEMENT FOR 总结了所有的放置选项，并以规范形式展示指定表、数据库模式或分区的放置信息。

Note

该功能在 平凯数据库云服务 Starter 和 平凯数据库云服务 Essential 实例中不可用。

该语句返回的结果集中，Scheduling_State 字段表示 Placement Driver（PD）在调度放置规则时的当前进度：

  • PENDING：PD 尚未开始调度放置规则。这可能表示放置规则在语义上是正确的，但当前集群无法满足。例如，若 FOLLOWERS=4，但只有 3 个 TiKV 节点可作为 follower。
  • INPROGRESS：PD 正在调度放置规则。
  • SCHEDULED：PD 已成功调度放置规则。

语法

ShowStmt
SHOW PLACEMENT FOR ShowPlacementTarget
ShowPlacementTarget
DatabaseSym DBName TABLE TableName TABLE TableName PARTITION Identifier

示例

CREATE PLACEMENT POLICY p1 PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4;
ALTER DATABASE test PLACEMENT POLICY=p1;
CREATE TABLE t1 (a INT);
SHOW PLACEMENT FOR DATABASE test;
SHOW PLACEMENT FOR TABLE t1;
SHOW CREATE TABLE t1\G
CREATE TABLE t3 (a INT) PARTITION BY RANGE (a) (PARTITION p1 VALUES LESS THAN (10), PARTITION p2 VALUES LESS THAN (20));
SHOW PLACEMENT FOR TABLE t3 PARTITION p1\G
Query OK, 0 rows affected (0.02 sec)

Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

+---------------+----------------------------------------------------------------------+------------------+
| Target        | Placement                                                            | Scheduling_State |
+---------------+----------------------------------------------------------------------+------------------+
| DATABASE test | PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 | INPROGRESS       |
+---------------+----------------------------------------------------------------------+------------------+
1 row in set (0.00 sec)

+---------------+-------------+------------------+
| Target        | Placement   | Scheduling_State |
+---------------+-------------+------------------+
| TABLE test.t1 | FOLLOWERS=4 | INPROGRESS       |
+---------------+-------------+------------------+
1 row in set (0.00 sec)

***************************[ 1. row ]***************************
Table        | t1
Create Table | CREATE TABLE `t1` (
  `a` int DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /*T![placement] PLACEMENT POLICY=`p1` */
1 row in set (0.00 sec)

***************************[ 1. row ]***************************
Target           | TABLE test.t3 PARTITION p1
Placement        | PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4
Scheduling_State | PENDING
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