From: Arne Roland <A.Roland@index.de>
To: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Disabling options lowers the estimated cost of a query
Date: Thu, 25 Feb 2021 23:07:08 +0000
Message-ID: <1581042da8044e71ada2d6e3a51bf7bb@index.de> (raw)
Hi,
I want to examine the exhaustive search and not the geqo here. I'd expect the exhaustive search to give the plan with the lowest cost, but apparently it doesn't. I have found a few dozen different querys where that isn't the case. I attached one straight forward example. For the join of two partitions a row first approach would have been reasonable.
Please note that I have enable_partitionwise_join on.
Both tables are partitioned by si, agv and have a primary key leading with si, agv.
I know that for this particular query the planning time dominates the execution time, but that is not my issue here. It's more a synthetic boiled down example coming from a more complex one with notably higher execution time.
Thank you for having a look!
Regards
Arne
Attachments:
exhaustive_search.txt (text/plain, 271.7K) download
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To: pgsql-performance@postgresql.org
Cc: A.Roland@index.de
Subject: Re: Disabling options lowers the estimated cost of a query
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