From: Itai Zukerman <zukerman@math-hat.com>
To: josh@agliodbs.com
Cc: pgsql-sql@postgresql.org
Subject: Re: count(*), EXISTS, indexes
Date: Fri, 11 Apr 2003 18:02:37 -0400
Message-ID: <87he94r8ua.fsf@matt.w80.math-hat.com> (raw)
In-Reply-To: <200304111442.48107.josh@agliodbs.com>
References: <874r54sr8q.fsf@matt.w80.math-hat.com>
<200304111353.50162.josh@agliodbs.com>
<871y08sq0e.fsf@matt.w80.math-hat.com>
<200304111442.48107.josh@agliodbs.com>
>> # explain select sum(weight) from rprofile rp where exists (select 1 from
> rcount_prof rcp where rcp.profile ~<= rp.profile and ~rcp.psig ~<= rp.psig
> and rcp.filter='{734,1944}');
>
> I'm not familiar with the "~" that you have in the query. What are those for?
They are my own operators and functions. profile is a integer array
and the ~'s are subset operators. psig is a bit signature, "~" is
complement, and the ~ operators again are subset operators.
> Do you have an index on rcp.profile, rcp.psig, rcp.filter?
Yes, yes, and yes. ATM, though, there are only about 50 rows in
rcount_prof. The vast majority of time is spent scanning the
600,000-row rprofile table.
--
Itai Zukerman <http://www.math-hat.com/~zukerman/;
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To: pgsql-sql@postgresql.org
Cc: zukerman@math-hat.com, josh@agliodbs.com
Subject: Re: count(*), EXISTS, indexes
In-Reply-To: <87he94r8ua.fsf@matt.w80.math-hat.com>
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