Postgresql 获取分区表的表大小（Postgres 10+；）_Postgresql_Postgresql 10_Postgresql 11

Postgresql 获取分区表的表大小（Postgres 10+；）

postgresql

Postgresql 获取分区表的表大小（Postgres 10+；）,postgresql,postgresql-10,postgresql-11,Postgresql,Postgresql 10,Postgresql 11,我遇到了这个查询，其中以字节为单位显示了表、表大小、toast大小和索引大小： SELECT relname AS table_name, pg_size_pretty(pg_total_relation_size(relid)) AS total, pg_size_pretty(pg_relation_size(relid)) AS internal, pg_size_pretty(pg_table_size(relid) - pg_relation_size(relid))

我遇到了这个查询，其中以字节为单位显示了表、表大小、toast大小和索引大小：

SELECT
  relname AS table_name,
  pg_size_pretty(pg_total_relation_size(relid)) AS total,
  pg_size_pretty(pg_relation_size(relid)) AS internal,
  pg_size_pretty(pg_table_size(relid) - pg_relation_size(relid)) AS external,
  pg_size_pretty(pg_indexes_size(relid)) AS indexes
FROM pg_catalog.pg_statio_user_tables 
ORDER BY pg_total_relation_size(relid) DESC;

我知道Postgres正在为每个分区创建一个表，因此我将分别为每个分区获取条目，但是否有方法可以为每个表获取一行，而不管该表是否已分区？

当然，但您必须与一组其他目录表合并，并使用

GROUP BY

目录
```
pg_class
```
中的属性
```
relkind
```
将告诉您一个关系是分区的（
```
p
```
），还是不分区的（
```
r
```
）
目录
```
pg_inherits
```
将告诉您哪个分区（
```
inhrelid
```
）属于哪个分区表（
```
inhparent
```
）

由于分区可以再次分区，如果您想覆盖所有的基，就必须编写一个递归公共表表达式。

按照@Laurenz的指示，尽管我创建了一个满足需要的查询。这将获得特定数据库中所有分区表的总内存

SELECT
   pi.inhparent::regclass AS parent_table_name, 
   pg_size_pretty(sum(pg_total_relation_size(psu.relid))) AS total,
   pg_size_pretty(sum(pg_relation_size(psu.relid))) AS internal,
   pg_size_pretty(sum(pg_table_size(psu.relid) - pg_relation_size(psu.relid))) AS external, -- toast
   pg_size_pretty(sum(pg_indexes_size(psu.relid))) AS indexes
FROM pg_catalog.pg_statio_user_tables psu
   JOIN pg_class pc ON psu.relname = pc.relname
   JOIN pg_database pd ON pc.relowner = pd.datdba
   JOIN pg_inherits pi ON pi.inhrelid = pc.oid
WHERE pd.datname = :database_name
GROUP BY pi.inhparent
ORDER BY sum(pg_total_relation_size(psu.relid)) DESC;

请注意，在分区的情况下，根表不会有一行，但每个父表都有自己的行，即使有多个分区级别，这也会为每个父表提供表大小：

WITH RECURSIVE tables AS (
  SELECT
    c.oid AS parent,
    c.oid AS relid,
    1     AS level
  FROM pg_catalog.pg_class c
  LEFT JOIN pg_catalog.pg_inherits AS i ON c.oid = i.inhrelid
    -- p = partitioned table, r = normal table
  WHERE c.relkind IN ('p', 'r')
    -- not having a parent table -> we only get the partition heads
    AND i.inhrelid IS NULL
  UNION ALL
  SELECT
    p.parent         AS parent,
    c.oid            AS relid,
    p.level + 1      AS level
  FROM tables AS p
  LEFT JOIN pg_catalog.pg_inherits AS i ON p.relid = i.inhparent
  LEFT JOIN pg_catalog.pg_class AS c ON c.oid = i.inhrelid AND c.relispartition
  WHERE c.oid IS NOT NULL
)
SELECT
  parent ::REGCLASS                                  AS table_name,
  array_agg(relid :: REGCLASS)                       AS all_partitions,
  pg_size_pretty(sum(pg_total_relation_size(relid))) AS pretty_total_size,
  sum(pg_total_relation_size(relid))                 AS total_size
FROM tables
GROUP BY parent
ORDER BY sum(pg_total_relation_size(relid)) DESC

实际上，每个分区只需要一行。用

psu.relname

替换group by中的

pi.inhparent

，并将select中的

pi.inhparent:：regclass替换为win的父表名称。