From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ayub Khan <ayub.hp@gmail.com>
Cc: Pgsql Performance <pgsql-performance@lists.postgresql.org>
Subject: Re: slow query
Date: Tue, 08 Jun 2021 13:14:28 -0400
Message-ID: <1121000.1623172468@sss.pgh.pa.us> (raw)
In-Reply-To: <CAHdeyE+Rhk646X4E2_dH6g-CD_nU8LJ=15XYvb7jjf8gid71Yw@mail.gmail.com>
References: <CAHdeyE+Rhk646X4E2_dH6g-CD_nU8LJ=15XYvb7jjf8gid71Yw@mail.gmail.com>
Ayub Khan <ayub.hp@gmail.com> writes:
> I checked all the indexes are defined on the tables however the query seems
> slow, below is the plan. Can any one give any pointers to verify ?
You might try to do something about the poor selectivity estimate here:
> -> Index Scan using
> menu_item_restaurant_id on menu_item a (cost=0.42..177.31 rows=1
> width=87) (actual time=0.130..3.769 rows=89 loops=1)
> Index Cond: (restaurant_id = 1528)
> " Filter: ((active =
> 'Y'::bpchar) AND (is_menu_item_available(menu_item_id, 'Y'::bpchar) =
> 'Y'::bpchar))"
> Rows Removed by Filter: 194
If the planner realized that this'd produce O(100) rows not 1,
it'd likely have picked a different plan. I'm guessing that
the issue is lack of knowledge about what is_menu_item_available()
will do. Maybe you could replace that with a status column?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, ayub.hp@gmail.com, pgsql-performance@lists.postgresql.org
Subject: Re: slow query
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