From: Qingqing Zhou <zhouqq@cs.toronto.edu>
To: pgsql-performance@postgresql.org
Subject: Re: slow "IN" clause
Date: Mon, 10 Apr 2006 12:44:46 +0800
Message-ID: <e1co2g$17eh$1@news.hub.org> (raw)
References: <1144640620.925899.274170@z34g2000cwc.googlegroups.com>
<FavoYang@gmail.com> wrote
> I have a slow sql:
> SELECT * FROM mytable WHERE id IN (1,3,5,7,....3k here...);
> mytable is about 10k rows.
>
> if don't use the "IN" clause, it will cost 0,11 second, otherwise it
> will cost 2.x second
> I guess pg use linear search to deal with IN clause, is there any way
> to let pg use other search method with IN clause? (ex.Binary Search or
> hash Search)
>
If you can put (1, 3, .., 3k) in a table, PG may choose a hash join.
Regards,
Qingqing
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To: pgsql-performance@postgresql.org
Cc: zhouqq@cs.toronto.edu
Subject: Re: slow "IN" clause
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