Date: Fri, 4 Sep 2020 23:36:35 +0200
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Nagaraj Raj <nagaraj.sf@yahoo.com>
Cc: Pgsql Performance <pgsql-performance@lists.postgresql.org>
Subject: Re: Query performance issue
Message-ID: <20200904213635.hvz2pxmmj3tatv26@development>
References: <975305787.3395625.1599254321500.ref@mail.yahoo.com>
 <975305787.3395625.1599254321500@mail.yahoo.com>
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On Fri, Sep 04, 2020 at 09:18:41PM +0000, Nagaraj Raj wrote:
> I have a query which will more often run on DB and very slow and it is doing 'seqscan'. I was trying to optimize it by adding indexes in different ways but nothing helps.
>Any suggestions?
>

1) It's rather difficult to read the query plan as it's mangled by your
e-mail client. I recommend to check how to prevent the client from doing
that, or attaching the plan as a file.

2) The whole query takes ~3500ms, and the seqscan only accounts for
~200ms, so it's very clearly not the main issue.

3) Most of the time is spent in sort, so the one thing you can do is
either increasing work_mem, or adding index providing that ordering.
Even better if you include all necessary columns to allow IOS.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services