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Re: Example code Re: Singleton SELECT inside cursor loop - Mailing list pgsql-general

From Christoph Moench-Tegeder
Subject Re: Example code Re: Singleton SELECT inside cursor loop
Date
Msg-id Yzgwu2MHvqlfkdwH@elch.exwg.net
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In response to Example code Re: Singleton SELECT inside cursor loop  (Ron <ronljohnsonjr@gmail.com>)
Responses Re: Example code Re: Singleton SELECT inside cursor loop
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## Ron (ronljohnsonjr@gmail.com):

> Note how quickly it runs the first five times, but takes 780x longer the 
> sixth time I run it.  Exiting psql and entering again causes the same 
> slowness the sixth time it's run.

Tanks at the sixth time? That rings a bell: "The current rule for this
is that the first five executions are done with custom plans[...]" from
https://www.postgresql.org/docs/12/sql-prepare.html
And your functions create prepared statements under the hood:
https://www.postgresql.org/docs/12/plpgsql-implementation.html#PLPGSQL-PLAN-CACHING
I guess you should visit
https://www.postgresql.org/docs/12/runtime-config-query.html#GUC-PLAN-CACHE_MODE
and try if plan_cache_mode = force_custom_plan helps here.

Regards,
Christoph

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