Message-ID: <4fb700b7a1f03d88447b40e830a4797ce026a0dc.camel@cybertec.at>
Subject: Re: AW: Trying to understand Tuple Header
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: "Subramanian,Ramachandran" <ramachandran.subramanian@alte-leipziger.de>,
  "David G. Johnston" <david.g.johnston@gmail.com>
Cc: "pgsql-novice@lists.postgresql.org" <pgsql-novice@lists.postgresql.org>
Date: Mon, 04 May 2026 09:32:52 +0200
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On Mon, 2026-05-04 at 04:04 +0000, Subramanian,Ramachandran wrote:
> So the next select to the table cross references the pg_xact file to chec=
k if hint bits
> need to be updated or not ?=C2=A0 How deep does the next select look into=
 the pg_xact file ?
> For example if I roll back and never touch this table for 30=C2=A0 Minute=
s and I come back
> and do a second select=E2=80=A6will it look back into 30 mins of history =
in pg_xact ?

Yes.  It has to, to maintain correctness.

If nobody ever looks at the row, eventually autovacuum will freeze it.  Any=
 pg_xact
segment that only contains transactions older than the oldest unfrozen row =
will
get reclaimed.

Yours,
Laurenz Albe