PURGE_PARTITION
清除已删除行的表分区。类似 PURGE 和 PURGE_PROJECTION，该函数会从物理存储中移除已删除的数据，这样可以重复使用磁盘空间。 PURGE_PARTITION 仅移除
AHM 时期及更早时期的数据。
这是元函数。您必须在顶级 SELECT 语句中调用元函数。
行为类型
易变语法
PURGE_PARTITION ( '[[database.]schema.]table', partition‑key )
参数
-
[database.]schema 数据库和架构。默认架构为
public。如果指定一个数据库，它必须是当前数据库。-
表 - 要清除的已分区的表。
-
partition‑key - 要清除的分区的键。
特权
-
表所有者
-
对架构的 USAGE 权限
示例
以下示例列出了表中每个分区已删除行的数量，然后调用 PURGE_PARTITION() 从数据清除已删除的行。
=> SELECT partition_key,table_schema,projection_name,sum(deleted_row_count)
AS deleted_row_count FROM partitions
GROUP BY partition_key,table_schema,projection_name
ORDER BY partition_key;
partition_key | table_schema | projection_name | deleted_row_count
---------------+--------------+-----------------+-------------------
0 | public | t_super | 2
1 | public | t_super | 2
2 | public | t_super | 2
3 | public | t_super | 2
4 | public | t_super | 2
5 | public | t_super | 2
6 | public | t_super | 2
7 | public | t_super | 2
8 | public | t_super | 2
9 | public | t_super | 1
(10 rows)
=> SELECT PURGE_PARTITION('t',5); -- Purge partition with key 5.
purge_partition
------------------------------------------------------------------------
Task: merge partitions
(Table: public.t) (Projection: public.t_super)
(1 row)
=> SELECT partition_key,table_schema,projection_name,sum(deleted_row_count)
AS deleted_row_count FROM partitions
GROUP BY partition_key,table_schema,projection_name
ORDER BY partition_key;
partition_key | table_schema | projection_name | deleted_row_count
---------------+--------------+-----------------+-------------------
0 | public | t_super | 2
1 | public | t_super | 2
2 | public | t_super | 2
3 | public | t_super | 2
4 | public | t_super | 2
5 | public | t_super | 0
6 | public | t_super | 2
7 | public | t_super | 2
8 | public | t_super | 2
9 | public | t_super | 1
(10 rows)