MIME-Version: 1.0
References: 
 <CAA4eK1L74EUU7+Dr11joY+Xact_MsjZu9G12sX+vRUWJsptP8Q@mail.gmail.com>
 <CAA4eK1+ORhnb2zUUpO_FcgWUUbwvQX5+=tdCehx7x2nB2x8VMg@mail.gmail.com>
 <CAD21AoCoX+jhy_i3v+T2s78NG_0HH1oXOUiTOWhDdxVPBtDHKA@mail.gmail.com>
 <CAJpy0uAwz9iNw3=5QC8S3z8Bf-w0z27rE32SFxjDMer7aTQMPg@mail.gmail.com>
 <CAA4eK1+q8R=yEpTMiOZ_Xksdd_Jg3SXvBMxRutHQtkCbdeK_yQ@mail.gmail.com>
 <CAJpy0uAU+nzufQwSzyB2YmhPHHn71_=1zkauP4Ra32a_eqbcig@mail.gmail.com>
 <CAA4eK1KtwFg6Mr1MRnHUUfPotzc2=5UCTq_D2t8x0PM1Lyhk8g@mail.gmail.com>
 <CAD21AoA03f0QKYjiSymGcnROvh1X-3YSqyB-19mkRXt5dfaxFw@mail.gmail.com>
 <CAJpy0uCneiKeNuz3B91Wf2LRxAenD3fpaxYfdL09y9qHmvVp+w@mail.gmail.com>
 <CAJpy0uCJ7MKgZnKLAACd-AXN0VbWM5gVJ+GRJ1Za_A2UmF3R0A@mail.gmail.com>
 <ZaegJe9JpUiQeV+D@ip-10-97-1-34.eu-west-3.compute.internal>
 <CAJpy0uBrBc+YNxCGwCjXR+9UJZqM3QvjNq86cBy4K7kp_EXxhQ@mail.gmail.com>
 <CAA4eK1JFhbBf-LywUU0YJUTcKTFjZvbXi-42DwCd-xojWKhRXA@mail.gmail.com>
In-Reply-To: 
 <CAA4eK1JFhbBf-LywUU0YJUTcKTFjZvbXi-42DwCd-xojWKhRXA@mail.gmail.com>
From: shveta malik <shveta.malik@gmail.com>
Date: Fri, 19 Jan 2024 11:46:51 +0530
Message-ID: 
 <CAJpy0uD+ODUF+D0GX38F_UQYTqA8wvTEUPOCBa-9guLLRMhFWQ@mail.gmail.com>
Subject: Re: Synchronizing slots from primary to standby
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>,
 Masahiko Sawada <sawada.mshk@gmail.com>,
	"Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>,
 Dilip Kumar <dilipbalaut@gmail.com>,
	Peter Smith <smithpb2250@gmail.com>, Nisha Moond <nisha.moond412@gmail.com>,
	"Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
	Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
	Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
 Bruce Momjian <bruce@momjian.us>,
	Ashutosh Sharma <ashu.coek88@gmail.com>, Andres Freund <andres@anarazel.de>,
	pgsql-hackers <pgsql-hackers@postgresql.org>,
 Ajin Cherian <itsajin@gmail.com>,
	Alvaro Herrera <alvherre@alvh.no-ip.org>,
 shveta malik <shveta.malik@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: 
 <https://www.postgresql.org/message-id/CAJpy0uD%2BODUF%2BD0GX38F_UQYTqA8wvTEUPOCBa-9guLLRMhFWQ%40mail.gmail.com>
Precedence: bulk

On Fri, Jan 19, 2024 at 11:23=E2=80=AFAM Amit Kapila <amit.kapila16@gmail.c=
om> wrote:
>
> > > 5 =3D=3D=3D (coming from v62-0002)
> > > +       Assert(tuplestore_tuple_count(res->tuplestore) =3D=3D 1);
> > >
> > > Is it even possible for the related query to not return only one row?=
 (I think the
> > > "count" ensures it).
> >
> > I think you are right. This assertion was added sometime back on the
> > basis of feedback on hackers. Let me review that again. I can consider
> > this comment in the next version.
> >
>
> OTOH, can't we keep the assert as it is but remove "=3D 1" from
> "count(*) =3D 1" in the query. There shouldn't be more than one slot
> with same name on the primary. Or, am I missing something?

There will be 1 record max and 0 record if the primary_slot_name is
invalid. Keeping 'count(*)=3D1' gives the benefit that it will straight
away give us true/false indicating if we are good or not wrt
primary_slot_name. I feel Assert can be removed and we can simply
have:

        if (!tuplestore_gettupleslot(res->tuplestore, true, false, tupslot)=
)
                elog(ERROR, "failed to fetch primary_slot_name tuple");

thanks
Shveta