Re: Intermittent errors when fetching cursor rows on PostgreSQL 16

On Wed, Dec 18, 2024 at 5:01 AM Enrico Schenone <eschenone(at)cleistech(dot)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 and
> 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.

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