Message-ID: <9565562b389eb3c105588d3c218907f84d0a2fa9.camel@cybertec.at>
Subject: Re: backend_xid and backend_xmin
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Satalabaha Postgres <satalabaha.postgres@gmail.com>,
	pgsql-admin@lists.postgresql.org
Date: Thu, 08 Dec 2022 21:46:12 +0100
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On Thu, 2022-12-08 at 21:01 +0530, Satalabaha Postgres wrote:
> I would like to understand the possible causes for backend_xmin getting
> populated  in pg_stat_activity. Can someone throw some light on this?

"backend_xid" is set when the session has an open transaction that has
modified data and therefore got a transaction ID.

"backend_xmin" is set if there is an active snapshot held by the session:
- there is a running query
- there is an open transaction with an open cursor
- there is an open transaction with isolation level REPEATABLE READ or higher

Yours,
Laurenz Albe
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