| title | summary |
|---|---|
SHOW PLACEMENT FOR |
TiDB 数据库中 SHOW PLACEMENT FOR 的使用概况。 |
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 FOR 用于汇总直接放置 (direct placement) 和放置策略 (placement policy) 中所有的放置选项，并为特定表、数据库或分区以规范形式呈现这些选项信息。
ShowStmt ::=
"PLACEMENT" "FOR" ShowPlacementTarget
ShowPlacementTarget ::=
DatabaseSym DBName
| "TABLE" TableName
| "TABLE" TableName "PARTITION" Identifier
{{< copyable "sql" >}}
CREATE PLACEMENT POLICY p1 PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4;
use test;
ALTER DATABASE test PLACEMENT POLICY=p1;
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (a INT) PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4;
SHOW PLACEMENT FOR DATABASE test;
SHOW PLACEMENT FOR TABLE t1;
SHOW CREATE TABLE t1\G
SHOW PLACEMENT FOR TABLE t2;
CREATE TABLE t3 (a INT) PARTITION BY RANGE (a) (PARTITION p1 VALUES LESS THAN (10), PARTITION p2 VALUES LESS THAN (20) FOLLOWERS=4);
SHOW PLACEMENT FOR TABLE t3 PARTITION p1;
SHOW PLACEMENT FOR TABLE t3 PARTITION p2;Query OK, 0 rows affected (0.02 sec)
Query OK, 0 rows affected (0.00 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(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /*T![placement] PLACEMENT POLICY=`p1` */
1 row in set (0.00 sec)
+---------------+----------------------------------------------------------------------+------------------+
| Target | Placement | Scheduling_State |
+---------------+----------------------------------------------------------------------+------------------+
| TABLE test.t2 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4 | INPROGRESS |
+---------------+----------------------------------------------------------------------+------------------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.14 sec)
+----------------------------+-----------------------------------------------------------------------+------------------+
| Target | Placement | Scheduling_State |
+----------------------------+-----------------------------------------------------------------------+------------------+
| TABLE test.t3 PARTITION p1 | 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.t3 PARTITION p2 | FOLLOWERS=4 | INPROGRESS |
+----------------------------+-------------+------------------+
1 row in set (0.00 sec)该语句是 TiDB 对 MySQL 语法的扩展。