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help / color / mirror / Atom feedFrom: Laurenz Albe <laurenz.albe@cybertec.at>
To: Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>
To: David G. Johnston <david.g.johnston@gmail.com>
Cc: pgsql-novice@lists.postgresql.org <pgsql-novice@lists.postgresql.org>
Subject: Re: AW: Trying to understand Tuple Header
Date: Mon, 04 May 2026 09:32:52 +0200
Message-ID: <4fb700b7a1f03d88447b40e830a4797ce026a0dc.camel@cybertec.at> (raw)
In-Reply-To: <544e6b78efba44e5b004a12a8460aa12@alte-leipziger.de>
References: <0f8e5544ae8a412bb637fcc3d15f8aaa@alte-leipziger.de>
<CAKFQuwawOYYR=Dfa3tWsKOd-baJ-hV7SKMj9FHiMnd9f-=vNAg@mail.gmail.com>
<b2202bde6eb145bb814806b5606d131a@alte-leipziger.de>
<CAKFQuwbRKbjk4JPefgT6s64hN-i47a1nZO6O4j-+h48er6uyvw@mail.gmail.com>
<544e6b78efba44e5b004a12a8460aa12@alte-leipziger.de>
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 check if hint bits
> need to be updated or not ? 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 Minutes and I come back
> and do a second select…will 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
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To: pgsql-novice@postgresql.org
Cc: laurenz.albe@cybertec.at, ramachandran.subramanian@alte-leipziger.de, david.g.johnston@gmail.com, pgsql-novice@lists.postgresql.org
Subject: Re: AW: Trying to understand Tuple Header
In-Reply-To: <4fb700b7a1f03d88447b40e830a4797ce026a0dc.camel@cybertec.at>
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