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From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Wed, 21 Feb 2024 20:10:00 +0530
Message-ID: <CALj2ACWbR9ck1PKyqT2agd2XCEq8L=D=X1Uw566yhA9SgXspAw@mail.gmail.com>
Subject: Re: Introduce XID age and inactive timeout based replication slot invalidation
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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On Wed, Feb 21, 2024 at 5:55=E2=80=AFPM Bertrand Drouvot
<bertranddrouvot.pg@gmail.com> wrote:
>
> > As far as the 0001 patch is concerned, it reports the
> > invalidation_reason as long as slot_contents.data.invalidated !=3D
> > RS_INVAL_NONE. I think this is okay.
> >
> > Thoughts?
>
> Yeah, looking at the code I agree that looks ok. OTOH, that looks confusi=
ng,
> maybe we should add a few words about it in the doc?

I'll think about it.

> Looking at v5-0001:
>
> +      <entry role=3D"catalog_table_entry"><para role=3D"column_definitio=
n">
> +       <structfield>invalidation_reason</structfield> <type>text</type>
> +      </para>
> +      <para>
>
> My initial thought was to put "conflict" value in this new field in case =
of
> conflict (not to mention the conflict reason in it). With the current pro=
posal
> invalidation_reason could report the same as conflict_reason, which sound=
s weird
> to me.
>
> Does that make sense to you to use "conflict" as value in "invalidation_r=
eason"
> when the slot has "conflict_reason" not NULL?

I'm thinking the other way around - how about we revert
https://git.postgresql.org/gitweb/?p=3Dpostgresql.git;a=3Dcommitdiff;h=3D00=
7693f2a3ac2ac19affcb03ad43cdb36ccff5b5,
that is, put in place "conflict" as a boolean and introduce
invalidation_reason the text form. So, for logical slots, whenever the
"conflict" column is true, the reason is found in invaldiation_reason
column? How does it sound? Again the debate might be "conflict" vs
"invalidation", but that looks clean IMHO.

--=20
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com