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From: Thomas Kellerer <shammat@gmx.net>
To: pgsql-performance@lists.postgresql.org
Subject: Re: JOIN on partitions is very slow
Date: Mon, 23 Mar 2020 17:33:34 +0100
Message-ID: <7cdfd0d6-e4d3-7351-f13c-696460853657@gmx.net> (raw)
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Michael Lewis schrieb am 23.03.2020 um 17:16:
> Yes. I can tweak the query. Version of postgres is 9.5.15. I have
> about 20 partitions for company_sale_account table. I do have an
> index on company name.
>
> I need to use DISTINCT as i need to remove the duplicates.
>
>
> DISTINCT is a sign of improper joins most of the time in my
> experience. Often, just changing to group by is faster

As none of the columns of the joined table are used, most probably
this should be re-written as an EXISTS condition.
Then neither GROUP BY nor DISTINCT is needed.








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