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References: <446423eb-4a4e-4135-bbb8-4d0e5c7aac3b@cleistech.it>
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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Wed, 18 Dec 2024 10:11:54 -0500
Message-ID: <CANzqJaB3yq0dBVeRqP7bN+3uEDM8grWPJ+=f2wYEs7-Mq_36Eg@mail.gmail.com>
Subject: Re: Intermittent errors when fetching cursor rows on PostgreSQL 16
To: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Wed, Dec 18, 2024 at 5:01=E2=80=AFAM Enrico Schenone <eschenone@cleistec=
h.it>
wrote:

> Good day.
> My name is Enrico Schenone, from Genoa, Italy.
> I'm a software achitect working at Cleis Tech - Genoa - Italy  -
> http://gruppocleis.it
> Me and my team are using PostgreSQL v12 to v16 on Debian 10-12 and Ubuntu
> Server 22.04 LTS with no-cluster configuration.
> Our applications are developed with 4Js Genero platform (classified as
> LCAP) - https://4js.com
>
> I whish to report an issue where I can't say if it happens at server or
> client side (or both as well).
> The problem occurs occasionally and only when fetching rows from a
> server-side cursor. The related query may be complex with joins or very
> easy (just one static table with 86 rows without WHERE conditions).
> I have set the "debug5" verbosity level of PostgreSQL log and I have
> extracted from millions of log line those who are belonging to separate
> failing sessions/connections.
> At the same time I have extracted the related application log.
> For each failure reported into the client-side application log, I have a
> distinct PostgreSQL detailed log.
>
> Then I have merged client-side end server-side logs along the timeline an=
d
> I have observed what client and server does.
> For example (S: means PostgreSQL Server log, while C: means Client log):
>

Can you replicate the error in Prod using psql and cursors?

See
https://www.postgresql.org/docs/current/plpgsql-cursors.html#PLPGSQL-CURSOR=
-USING
Section 41.7.3.5.

--=20
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

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<div dir=3D"ltr"><div dir=3D"ltr">On Wed, Dec 18, 2024 at 5:01=E2=80=AFAM E=
nrico Schenone &lt;<a href=3D"mailto:eschenone@cleistech.it">eschenone@clei=
stech.it</a>&gt; wrote:</div><div class=3D"gmail_quote gmail_quote_containe=
r"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord=
er-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>

 =20

   =20
 =20
  <div>
    Good day.<br>
    My name is Enrico Schenone, from Genoa, Italy.<br>
    I&#39;m a software achitect working at Cleis Tech - Genoa - Italy=C2=A0=
 -
    <a href=3D"http://gruppocleis.it" target=3D"_blank">http://gruppocleis.=
it</a><br>
    Me and my team are using PostgreSQL v12 to v16 on Debian 10-12 and
    Ubuntu Server 22.04 LTS with no-cluster configuration.<br>
    Our applications are developed with 4Js Genero platform (classified
    as LCAP) - <a href=3D"https://4js.com" target=3D"_blank">https://4js.co=
m</a><br>
    <br>
    I whish to report an issue where I can&#39;t say if it happens at serve=
r
    or client side (or both as well).<br>
    <span lang=3D"en"><span><span>The problem occurs occasionally and only =
when
          fetching rows from a server-side cursor. The related query may
          be complex with joins or very easy (just one static table with
          86 rows without WHERE conditions).<br>
          I have set the &quot;debug5&quot; verbosity level of PostgreSQL l=
og and
          I have extracted from millions of log line those who are
          belonging to separate failing sessions/connections.<br>
          At the same time I have extracted the related application log.<br=
>
          For each failure reported into the client-side application
          log, I have a distinct PostgreSQL detailed log.<br>
          <br>
          Then I have merged client-side end server-side logs along the
          timeline and I have observed what client and server does.<br>
          For example (S: means PostgreSQL Server log, while C: means
          Client log):<br></span></span></span></div></blockquote><div><br>=
</div><div>Can you replicate the error in Prod using psql and cursors?</div=
><div><br></div><div>See=C2=A0<a href=3D"https://www.postgresql.org/docs/cu=
rrent/plpgsql-cursors.html#PLPGSQL-CURSOR-USING">https://www.postgresql.org=
/docs/current/plpgsql-cursors.html#PLPGSQL-CURSOR-USING</a> Section 41.7.3.=
5.</div></div><div><br></div><span class=3D"gmail_signature_prefix">-- </sp=
an><br><div dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr">Death to=
 &lt;Redacted&gt;, and butter sauce.<div>Don&#39;t boil me, I&#39;m still a=
live.<br><div><div>&lt;Redacted&gt; lobster!</div></div></div></div></div><=
/div>

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