Question

Following on from this prior question about relation sizes：

此查询：

query = "CREATE TEMPORARY TABLE query_out AS SELECT * FROM users WHERE is_admin = false"
ActiveRecord::Base.connection.execute(query)

将生成一个临时表并插入此查询中的所有记录，即

SELECT * FROM users WHERE is_admin = false

然后

ActiveRecord::Base.connection.execute("SELECT pg_size_pretty(pg_relation_size('query_out'))")

我只得到一张桌子的大小。

我需要做什么才能在一个查询中获得多个表的大小？

任何帮助都将不胜感激。

由于

它将给出该临时表的大小。

Answer 1

以下选择查询将返回所有表及其大小的

SELECT
   relname as mytable,
   pg_size_pretty(pg_relation_size(relid)) As size
   FROM pg_catalog.pg_statio_user_tables ORDER BY pg_total_relation_size(relid) DESC;

使用此选择

创建一个VIEW

CREATE VIEW vTableAndSize AS 
SELECT
   relname as mytable,
   pg_size_pretty(pg_relation_size(relid)) As size
   FROM pg_catalog.pg_statio_user_tables ORDER BY pg_total_relation_size(relid) DESC;

现在你可以查询这个视图来获得像这样的大小

SELECT mytable,size 
       FROM vTableAndSize WHERE mytable in ('table1','table2')

根据OP's Comment

CREATE VIEW vTableAndSize_1 as 
SELECT
   relname as mytable,
   (pg_relation_size(relid)) As size
   FROM pg_catalog.pg_statio_user_tables ORDER BY pg_total_relation_size(relid) DESC;

使用

获取多列的大小和

/* Get sum of specific tables */
SELECT pg_size_pretty(sum(size)) tablesizesum 
       FROM vTableAndSize_1 WHERE mytable in ('table1','table2')

/* Get sum of all tables */
SELECT pg_size_pretty(sum(size)) tablesizesum 
       FROM vTableAndSize_1

在vTableAndSize_1数据库中创建PostgreSQL并在前端查询如下（我不熟悉Ruby ）

ActiveRecord::Base.connection.execute("SELECT pg_size_pretty(sum(size)) FROM vTableAndSize_1 
WHERE mytable in ('table1','table2')")

在一个查询POSTGRES中获取多个表的大小？

1 个答案: