Re: Doc limitation update proposal: include out-of-line OID usage per TOAST-ed columns

From: Nikita Malakhov <hukutoc(at)gmail(dot)com>
To: Jakub Wartak <jakub(dot)wartak(at)enterprisedb(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Doc limitation update proposal: include out-of-line OID usage per TOAST-ed columns
Date: 2023-04-21 07:14:01
Message-ID: CAN-LCVOKdemAwFrnntGNSpM4WiVHdYUSMcXzWuKiS5q3vvwg2Q@mail.gmail.com
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Hi!

This limitation applies not only to wide tables - it also applies to tables
where TOASTed values
are updated very often. You would soon be out of available TOAST value ID
because in case of
high frequency updates autovacuum cleanup rate won't keep up with the
updates. It is discussed
in [1].

On Fri, Apr 21, 2023 at 9:39 AM Jakub Wartak <jakub(dot)wartak(at)enterprisedb(dot)com>
wrote:

> Hi -hackers,
>
> I would like to ask if it wouldn't be good idea to copy the
> https://wiki.postgresql.org/wiki/TOAST#Total_table_size_limit
> discussion (out-of-line OID usage per TOAST-ed columns / potential
> limitation) to the official "Appendix K. PostgreSQL Limits" with also
> little bonus mentioning the "still searching for an unused OID in
> relation" notice. Although it is pretty obvious information for some
> and from commit 7fbcee1b2d5f1012c67942126881bd492e95077e and the
> discussion in [1], I wonder if the information shouldn't be a little
> more well known via the limitation (especially to steer people away
> from designing very wide non-partitioned tables).
>
> Regards,
> -J.
>
> [1] -
> https://www.postgresql.org/message-id/flat/16722-93043fb459a41073%40postgresql.org
>
>
>
[1]
https://www.postgresql.org/message-id/CAN-LCVPRvRzxeUdYdDCZ7UwZQs1NmZpqBUCd%3D%2BRdMPFTyt-bRQ%40mail.gmail.com

--
Regards,
Nikita Malakhov
Postgres Professional
The Russian Postgres Company
https://postgrespro.ru/

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