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From: Laurenz Albe <[email protected]>
To: Subramanian,Ramachandran <[email protected]>
To: David G. Johnston <[email protected]>
Cc: [email protected] <[email protected]>
Subject: Re: AW: Trying to understand Tuple Header
Date: Mon, 04 May 2026 09:32:52 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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	<[email protected]>
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	<[email protected]>

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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