Subject: Re: Performance of SELECT directly and from application
To: Pgsql-admin <pgsql-admin@postgresql.org>
References: <404eece7-44b3-bbb4-177a-ff955d10e7e6@vit.de>
 <9dda6f8fa24bb80c7456a8439cba0b4adf2b8ae4.camel@cybertec.at>
From: Jessica Holle <jessica.holle@vit.de>
Message-ID: <7ee1fb6b-b1d2-f69b-7a28-e37c32c696fc@vit.de>
Date: Thu, 25 Jun 2020 13:13:46 +0200
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Thanks for this advice.

We found out, that application use the following paramters:
set max_parallel_workers_per_gather to 4;
set min_parallel_table_scan_size = '1MB';
set parallel_setup_cost = 10;
set parallel_tuple_cost = 0.001;

Now they are using standardparamteers and they have restart Wildfly with 
deleting tmp and -surprize- as fast as before.

I'm not allowed to post the plan until it is anonymized.

Until now thanks for helping.

Kind regards, Jessica

Am 24.06.20 um 08:14 schrieb Laurenz Albe:
> On Wed, 2020-06-24 at 07:00 +0200, Jessica Holle wrote:
>> we use PostgreSQL 12.3.1 and have a little bit trouble with performance.
>> When the statement comes from the application (wildfly) duration is
>> about 24982.819 ms. When I do the statement directly with psql duration
>> is 967.773 ms.
>> Duration from Wildfly is known becaue we use in postgresql.conf
>> "log_min_duration_statement = 5000". There I see, that from application
>> are 3 variables used.
>> Is there any idea why this can happen or a hint to solve this issue?
> Try using "auto_explain" to get EXPLAIN (ANALYZE, BUFFERS) output for the slow
> execution.  The comparison of these two execution plans would be instructive.
>
> Does the application set any parameters?  Does it use a cursor?
>
> Yours,
> Laurenz Albe

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