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Re: Mysterious performance degradation in exceptional cases

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On 9/18/22 02:30, Matthias Apitz wrote:
El día jueves, septiembre 15, 2022 a las 08:40:24a. m. -0700, Adrian Klaver escribió:

On 9/14/22 22:33, Matthias Apitz wrote:
El día miércoles, septiembre 14, 2022 a las 07:19:31a. m. -0700, Adrian Klaver escribió:

On 9/14/22 01:31, Matthias Apitz wrote:


The 'app-server' does not answer, but does the database not answer also?

Have you looked to see if the database is providing a response in a timely
manner and if it is getting 'lost' in the 'app-server'?

I do not "think" that the time is spent elsewhere in the 'app-server'.
to make a fact of the "thinking", I enabled the tracing of our dblayer
showing how many milliseconds have been spent between entering the dblayer and
returning the result to the application layers. This is in effect since
36 hours now. Since September 13 the problem has not showed up anymore.
We are waiting for it...

Is this with or without your every 10 sec 'ping' search program?


Also have you considered Tom Lane's suggestion of using auto_explain?

I'm afraid that this would affect all other applications using the same
server. We still have other options to use. When the above tracing shows
a result, i.e. which of the high level operations of the dblayer uses
more time (more milliseconds) than normal, the next level is the detailed logging
of the ESQL/C operations (where we added time stamps which normaly this
logging does not have in its source code).

You can load auto_explain per session as shown here:

https://www.postgresql.org/docs/current/auto-explain.html

F.4.2. Example


Thanks

	matthias



--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx





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