| title | summary | aliases | |
|---|---|---|---|
PLACEMENT_POLICIES |
了解 information_schema 表 `PLACEMENT_POLICIES`。 |
|
PLACEMENT_POLICIES 表展示所有放置策略 (placement policy) 的信息，见 Placement Rules in SQL。
{{< copyable "sql" >}}
USE information_schema;
DESC placement_policies;+----------------------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------------+---------------+------+-----+---------+-------+
| POLICY_ID | bigint(64) | NO | | <null> | |
| CATALOG_NAME | varchar(512) | NO | | <null> | |
| POLICY_NAME | varchar(64) | NO | | <null> | |
| PRIMARY_REGION | varchar(1024) | YES | | <null> | |
| REGIONS | varchar(1024) | YES | | <null> | |
| CONSTRAINTS | varchar(1024) | YES | | <null> | |
| LEADER_CONSTRAINTS | varchar(1024) | YES | | <null> | |
| FOLLOWER_CONSTRAINTS | varchar(1024) | YES | | <null> | |
| LEARNER_CONSTRAINTS | varchar(1024) | YES | | <null> | |
| SCHEDULE | varchar(20) | YES | | <null> | |
| FOLLOWERS | bigint(64) | YES | | <null> | |
| LEARNERS | bigint(64) | YES | | <null> | |
+----------------------+---------------+------+-----+---------+-------+
12 rows in set (0.00 sec)PLACEMENT_POLICIES 表只展示放置策略 (placement policy) 的信息。如需查看所有信息的规范版本（放置策略，以及绑定放置策略的对象），请改用 SHOW PLACEMENT 语句：
{{< copyable "sql" >}}
CREATE TABLE t1 (a INT);
CREATE PLACEMENT POLICY p1 primary_region="us-east-1" regions="us-east-1";
CREATE TABLE t3 (a INT) PLACEMENT POLICY=p1;
SHOW PLACEMENT; -- 显示所有信息，包含 t3。
SELECT * FROM information_schema.placement_policies; -- 只显示放置策略，不包含 t3。Query OK, 0 rows affected (0.09 sec)
Query OK, 0 rows affected (0.11 sec)
Query OK, 0 rows affected (0.08 sec)
+---------------+------------------------------------------------+------------------+
| Target | Placement | Scheduling_State |
+---------------+------------------------------------------------+------------------+
| POLICY p1 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" | NULL |
| TABLE test.t3 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" | SCHEDULED |
+---------------+------------------------------------------------+------------------+
2 rows in set (0.00 sec)
+-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
| POLICY_ID | CATALOG_NAME | POLICY_NAME | PRIMARY_REGION | REGIONS | CONSTRAINTS | LEADER_CONSTRAINTS | FOLLOWER_CONSTRAINTS | LEARNER_CONSTRAINTS | SCHEDULE | FOLLOWERS | LEARNERS |
+-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
| 1 | def | p1 | us-east-1 | us-east-1 | | | | | | 2 | 0 |
+-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
1 rows in set (0.00 sec)