Re: Size of /pgdata

From: Raj <rajeshkumar(dot)dba09(at)gmail(dot)com>
To: Bhanu Prakash <mallelabhanuprakash(at)gmail(dot)com>
Cc: Pgsql-admin <pgsql-admin(at)lists(dot)postgresql(dot)org>
Subject: Re: Size of /pgdata
Date: 2026-06-13 07:15:05
Message-ID: CAJk5AtaAOREG8zk6UAGFQmeunfQ+vR+D5GmhURbqkRqNObEQDg@mail.gmail.com
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As I was saying I see relfilenode (say 324678).. du -sh 324678* list all
files....then totaled their size summing up 113Gb ...whereas actual table
size is 73gb

On Sat, 13 Jun 2026, 12:40 Raj, <rajeshkumar(dot)dba09(at)gmail(dot)com> wrote:

> Checked temp files as well...no thesee are not temp.files
>
> On Sat, 13 Jun 2026, 12:39 Bhanu Prakash, <mallelabhanuprakash(at)gmail(dot)com>
> wrote:
>
>> Probably, pgsql_tmp file might consumed rest of ~200gb disk. You will
>> find this inside base directory.
>>
>> During large query executions, if data to be sorted exceeds work_mem
>> settings, postgresql creates temporary files and spills data to disk.
>>
>> Possible reasons :
>> Poor query
>> Large batch jobs
>> Missing index
>> LRQ’s
>> Too low work_mem
>>
>> On Sat, 13 Jun 2026 at 12:18 PM, Raj <rajeshkumar(dot)dba09(at)gmail(dot)com> wrote:
>>
>>> Hi all,
>>>
>>> I am using 17.9 version.
>>>
>>> I see suddenly du -sh /pgdata/17 shows 930GB. Total allocated is 1TB.
>>>
>>> I checked the db size using \l+ and also pg_total_relation_size and size
>>> for particular db is 630GB. Ignoring postgres and template dbs as they are
>>> in KBs.
>>>
>>> Now where the remaining 300 comes from approximately..?
>>>
>>> I checked pg_wal and is 100gb..that is intended based on max_wal_size
>>> setting.
>>>
>>> Postgres logs also in MBs ..so ruling out that.
>>>
>>> Now 300 - 100 = 200gb approximately don't know where it comes from.
>>>
>>> So du -sh /base is approximately 830Gb whereas actual db size is 630gb
>>> as mentioned earlier.
>>>
>>> I took one big sample table which is 73GB, and using relfilenode(327683)
>>> I tried finding the underlying file size du -sh 327683* and able to find
>>> the total size the files occpuing and found 113gb.......so for one table
>>> itself it is 40Gb additional...
>>>
>>> I also checked the bloat of table using pgstatstuple and no bloat
>>> observed for this sample table
>>>
>>> Why we have so much increase of file size? How we can avoid or tune it?
>>> Is it about reallocating files and not being used fully? What's the
>>> solution?
>>>
>>>
>>>
>>>
>>>

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