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Date: Sun, 18 Dec 2022 11:55:01 -0300
From: "Euler Taveira" <euler@eulerto.com>
To: "Jaime Casanova" <jcasanov@systemguards.com.ec>,
 "jian he" <jian.universality@gmail.com>
Cc: pgsql-docs@lists.postgresql.org
Subject: Re: pg_stat_database view column xact_commit description should be
 more
 descriptive?
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On Fri, Dec 16, 2022, at 5:40 PM, Jaime Casanova wrote:
> I want to hijack this thread to say that xact_commit seems to be also
> counting COMMIT records received by logical replication.
> Should we explain that in documentation?
Probably. I don't think adding something to pg_stat_database is appropriate.
IMO this concept should be explained in the logical replication chapter [1].
Logical replication uses transaction infrastructure to apply changes, hence,
statistics will take it into account.

> What about physical replication? Are those also counted?
No. Physical replication does not use the transaction machinery to replicate
changes. It is in a lower layer and statistics don't apply at it.


[1] https://www.postgresql.org/docs/devel/logical-replication.html


--
Euler Taveira
EDB   https://www.enterprisedb.com/

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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Fri, Dec 16,=
 2022, at 5:40 PM, Jaime Casanova wrote:<br></div><blockquote type=3D"ci=
te" id=3D"qt" style=3D""><div>I want to hijack this thread to say that x=
act_commit seems to be also<br></div><div>counting COMMIT records receiv=
ed by logical replication.<br></div><div>Should we explain that in docum=
entation?<br></div></blockquote><div>Probably. I don't think adding some=
thing to pg_stat_database is appropriate.<br></div><div>IMO this concept=
 should be explained in the logical replication chapter [1].<br></div><d=
iv>Logical replication uses transaction infrastructure to apply changes,=
 hence,<br></div><div>statistics will take it into account.<br></div><di=
v><br></div><blockquote type=3D"cite" id=3D"qt" style=3D""><div>What abo=
ut physical replication? Are those also counted?<br></div></blockquote><=
div>No. Physical replication does not use the transaction machinery to r=
eplicate<br></div><div>changes. It is in a lower layer and statistics do=
n't apply at it.<br></div><div><br></div><div><br></div><div>[1] <a href=
=3D"https://www.postgresql.org/docs/devel/logical-replication.html">http=
s://www.postgresql.org/docs/devel/logical-replication.html</a><br></div>=
<div><br></div><div><br></div><div id=3D"sig112409080"><div class=3D"sig=
nature">--<br></div><div class=3D"signature">Euler Taveira<br></div><div=
 class=3D"signature">EDB&nbsp;&nbsp; <a href=3D"https://www.enterprisedb=
.com/">https://www.enterprisedb.com/</a><br></div></div><div><br></div><=
/body></html>
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