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From: sud <suds1434@gmail.com>
Date: Thu, 23 May 2024 18:15:17 +0530
Message-ID: <CAD=mzVVqR-mKUFHetsejFWSPQPbLjTVhCmBebJTFX5XmYp+nGg@mail.gmail.com>
Subject: Re: Long running query causing XID limit breach
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: pgsql-general <pgsql-general@lists.postgresql.org>
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On Thu, May 23, 2024 at 1:45=E2=80=AFPM Laurenz Albe <laurenz.albe@cybertec=
.at>
wrote:

>
>
> If a long running query on the standby influences the primary, that means
> that
> you have "hot_standby_feedback" set to "on".  Set it to "off".
>
>
> Will the setting up of "hot_standby_feedback" value to OFF will cause the
reader instance to give incorrect query results or unexpected query failure
which will be potential inconsistency between the writer and reader
instance, as because those XID's can be removed/cleaned by the writer node
even if its being read by the reader instance query. And it can have more
replication lag. So I'm wondering , if this setup is advisable one?

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><div class=3D"gmail_quote"><div=
 dir=3D"ltr" class=3D"gmail_attr">On Thu, May 23, 2024 at 1:45=E2=80=AFPM L=
aurenz Albe &lt;<a href=3D"mailto:laurenz.albe@cybertec.at">laurenz.albe@cy=
bertec.at</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=
=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding=
-left:1ex"><br>
<br>
If a long running query on the standby influences the primary, that means t=
hat<br>
you have &quot;hot_standby_feedback&quot; set to &quot;on&quot;.=C2=A0 Set =
it to &quot;off&quot;.<br>
<br><br></blockquote><div>Will the setting up of &quot;hot_standby_feedback=
&quot; value to OFF will cause the reader instance to give incorrect=C2=A0q=
uery results or unexpected query failure which will be potential inconsiste=
ncy between the writer and reader instance, as because those XID&#39;s can =
be removed/cleaned by the writer node even if its being read by the reader =
instance query. And it can have more replication lag. So I&#39;m wondering=
=C2=A0, if this setup is advisable one?</div></div></div>

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