PLACEMENT_POLICIES

PLACEMENT_POLICIES 表展示所有放置策略 (placement policy) 的信息，见 Placement Rules in SQL。

1. USE information_schema;
2. DESC placement_policies;

1. +----------------------+---------------+------+-----+---------+-------+
2. | Field                | Type          | Null | Key | Default | Extra |
3. +----------------------+---------------+------+-----+---------+-------+
4. | POLICY_ID            | bigint(64)    | NO   |     | <null>  |       |
5. | CATALOG_NAME         | varchar(512)  | NO   |     | <null>  |       |
6. | POLICY_NAME          | varchar(64)   | NO   |     | <null>  |       |
7. | PRIMARY_REGION       | varchar(1024) | YES  |     | <null>  |       |
8. | REGIONS              | varchar(1024) | YES  |     | <null>  |       |
9. | CONSTRAINTS          | varchar(1024) | YES  |     | <null>  |       |
10. | LEADER_CONSTRAINTS   | varchar(1024) | YES  |     | <null>  |       |
11. | FOLLOWER_CONSTRAINTS | varchar(1024) | YES  |     | <null>  |       |
12. | LEARNER_CONSTRAINTS  | varchar(1024) | YES  |     | <null>  |       |
13. | SCHEDULE             | varchar(20)   | YES  |     | <null>  |       |
14. | FOLLOWERS            | bigint(64)    | YES  |     | <null>  |       |
15. | LEARNERS             | bigint(64)    | YES  |     | <null>  |       |
16. +----------------------+---------------+------+-----+---------+-------+
17. 12 rows in set (0.00 sec)

示例

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：

1. CREATE TABLE t1 (a INT);
2. CREATE PLACEMENT POLICY p1 primary_region="us-east-1" regions="us-east-1";
3. CREATE TABLE t3 (a INT) PLACEMENT POLICY=p1;
4. SHOW PLACEMENT; -- 显示所有信息，包含 t3。
5. SELECT * FROM information_schema.placement_policies; -- 只显示放置策略，不包含 t3。

1. Query OK, 0 rows affected (0.09 sec)

3. Query OK, 0 rows affected (0.11 sec)

5. Query OK, 0 rows affected (0.08 sec)

7. +---------------+------------------------------------------------+------------------+
8. | Target        | Placement                                      | Scheduling_State |
9. +---------------+------------------------------------------------+------------------+
10. | POLICY p1     | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" | NULL             |
11. | TABLE test.t3 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" | SCHEDULED        |
12. +---------------+------------------------------------------------+------------------+
13. 2 rows in set (0.00 sec)

15. +-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
16. | POLICY_ID | CATALOG_NAME | POLICY_NAME | PRIMARY_REGION | REGIONS   | CONSTRAINTS | LEADER_CONSTRAINTS | FOLLOWER_CONSTRAINTS | LEARNER_CONSTRAINTS | SCHEDULE | FOLLOWERS | LEARNERS |
17. +-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
18. | 1         | def          | p1          | us-east-1      | us-east-1 |             |                    |                      |                     |          | 2         | 0        |
19. +-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
20. 1 rows in set (0.00 sec)