PLACEMENT_RULES

PLACEMENT_RULES 表展示所有已显式配置的 Placement Rules in SQL 信息，包括通过放置策略 (placement policy) 和通过直接放置 (directly placement) 进行配置的信息。

1. USE information_schema;
2. DESC placement_rules;

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(5)   | YES  |      | NULL    |       |
7. | SCHEMA_NAME          | varchar(5)   | YES  |      | NULL    |       |
8. | TABLE_NAME           | varchar(5)   | YES  |      | NULL    |       |
9. | PARTITION_NAME       | varchar(5)   | YES  |      | NULL    |       |
10. | PRIMARY_REGION       | varchar(5)   | NO   |      | NULL    |       |
11. | REGIONS              | varchar(5)   | NO   |      | NULL    |       |
12. | CONSTRAINTS          | varchar(5)   | NO   |      | NULL    |       |
13. | LEADER_CONSTRAINTS   | varchar(5)   | NO   |      | NULL    |       |
14. | FOLLOWER_CONSTRAINTS | varchar(5)   | NO   |      | NULL    |       |
15. | LEARNER_CONSTRAINTS  | varchar(5)   | NO   |      | NULL    |       |
16. | SCHEDULE             | varchar(20)  | NO   |      | NULL    |       |
17. | FOLLOWERS            | bigint(64)   | NO   |      | NULL    |       |
18. | LEARNERS             | bigint(64)   | NO   |      | NULL    |       |
19. +----------------------+--------------+------+------+---------+-------+
20. 15 rows in set (0.00 sec)

示例

PLACEMENT_RULES 表只展示显式配置的规则。如要查看 Placement Rules 放置规则的规范版本（包括附加到表格的放置策略），请改用 SHOW PLACEMENT 语句：

1. CREATE TABLE t1 (a INT);
2. CREATE TABLE t2 (a INT) primary_region="us-east-1" regions="us-east-1";
3. CREATE PLACEMENT POLICY p1 primary_region="us-east-1" regions="us-east-1";
4. CREATE TABLE t3 (a INT) PLACEMENT POLICY=p1;
5. SHOW PLACEMENT; -- 包含 t3。
6. SELECT * FROM information_schema.placement_rules; -- 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. Query OK, 0 rows affected (0.11 sec)

9. +---------------+------------------------------------------------+
10. | Target        | Placement                                      |
11. +---------------+------------------------------------------------+
12. | POLICY p1     | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" |
13. | TABLE test.t2 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" |
14. | TABLE test.t3 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" |
15. +---------------+------------------------------------------------+
16. 3 rows in set (0.00 sec)

18. +-----------+--------------+-------------+-------------+------------+----------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
19. | POLICY_ID | CATALOG_NAME | POLICY_NAME | SCHEMA_NAME | TABLE_NAME | PARTITION_NAME | PRIMARY_REGION | REGIONS   | CONSTRAINTS | LEADER_CONSTRAINTS | FOLLOWER_CONSTRAINTS | LEARNER_CONSTRAINTS | SCHEDULE | FOLLOWERS | LEARNERS |
20. +-----------+--------------+-------------+-------------+------------+----------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
21. |         3 | def          | p1          | NULL        | NULL       | NULL           | us-east-1      | us-east-1 |             |                    |                      |                     |          |         0 |        0 |
22. |      NULL | def          | NULL        | test        | t2         | NULL           | us-east-1      | us-east-1 |             |                    |                      |                     |          |         0 |        0 |
23. +-----------+--------------+-------------+-------------+------------+----------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
24. 2 rows in set (0.00 sec)