Re: AW: Trying to understand Tuple Header - Mailing list pgsql-novice

From Laurenz Albe
Subject Re: AW: Trying to understand Tuple Header
Date
Msg-id 4fb700b7a1f03d88447b40e830a4797ce026a0dc.camel@cybertec.at
Whole thread
In response to AW: Trying to understand Tuple Header  ("Subramanian,Ramachandran" <ramachandran.subramanian@alte-leipziger.de>)
List pgsql-novice
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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