Re: pg_relation_size on partitioned table - Mailing list pgsql-hackers

From Japin Li
Subject Re: pg_relation_size on partitioned table
Date
Msg-id MEYP282MB166934DA58F69D3714993A71B61A9@MEYP282MB1669.AUSP282.PROD.OUTLOOK.COM
Whole thread Raw
In response to Re: pg_relation_size on partitioned table  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
List pgsql-hackers
On Fri, 25 Mar 2022 at 20:59, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> On 2022-Mar-25, Japin Li wrote:
>
>> Could we provide a function to get the total size of the partition table
>> though the partitioned table name?  Maybe we can extend
>> the pg_relation_size() to get the total size of partition tables through
>> the partitioned table name.
>
> Does \dP+ do what you need?

Thanks for your quick response!

I find the \dP+ use the following SQL:

    SELECT n.nspname as "Schema",
      c.relname as "Name",
      pg_catalog.pg_get_userbyid(c.relowner) as "Owner",
      CASE c.relkind WHEN 'p' THEN 'partitioned table' WHEN 'I' THEN 'partitioned index' END as "Type",
      inh.inhparent::pg_catalog.regclass as "Parent name",
     c2.oid::pg_catalog.regclass as "Table",
      s.tps as "Total size",
      pg_catalog.obj_description(c.oid, 'pg_class') as "Description"
    FROM pg_catalog.pg_class c
         LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
         LEFT JOIN pg_catalog.pg_index i ON i.indexrelid = c.oid
         LEFT JOIN pg_catalog.pg_class c2 ON i.indrelid = c2.oid
         LEFT JOIN pg_catalog.pg_inherits inh ON c.oid = inh.inhrelid,
         LATERAL (SELECT pg_catalog.pg_size_pretty(sum(
                     CASE WHEN ppt.isleaf AND ppt.level = 1
                          THEN pg_catalog.pg_table_size(ppt.relid) ELSE 0 END)) AS dps,
                         pg_catalog.pg_size_pretty(sum(pg_catalog.pg_table_size(ppt.relid))) AS tps
                  FROM pg_catalog.pg_partition_tree(c.oid) ppt) s
    WHERE c.relkind IN ('p','I','')
      AND c.relname OPERATOR(pg_catalog.~) '^(parent)$' COLLATE pg_catalog.default
      AND pg_catalog.pg_table_is_visible(c.oid)
    ORDER BY "Schema", "Type" DESC, "Parent name" NULLS FIRST, "Name";


pg_table_size() includes "main", "vm", "fsm", "init" and "toast", however,
I only care about the "main" fork.

--
Regrads,
Japin Li.
ChengDu WenWu Information Technology Co.,Ltd.



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