From: Tom Lane <tgl@sss.pgh.pa.us>
To: Avdhoot Kishore Saple <Avdhoot_Saple@infosys.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: local selectivity estimation - computing frequency of predicates
Date: Fri, 13 Apr 2007 10:13:14 -0400
Message-ID: <18791.1176473594@sss.pgh.pa.us> (raw)
In-Reply-To: <54D17EC6EF3C114693F2F8117990AAC101A10233@BLRKECMSG13.ad.infosys.com>
References: <54D17EC6EF3C114693F2F8117990AAC101A10233@BLRKECMSG13.ad.infosys.com>
"Avdhoot Kishore Saple" <Avdhoot_Saple@infosys.com> writes:
> How to compute the frequency of predicate (e.g. Salary > $70000) in an
> SQL query from a DB's pre-defined indexes?". I'm specifically looking at
> how to retrieve information about indices (like number of pages at each
> level of index, range of attribute values etc.)
I don't think what you're looking for is exposed anywhere. Postgres
doesn't rely on indexes for statistical information anyway; the
pg_statistic system catalog (see also pg_stats view) is used for that.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, Avdhoot_Saple@infosys.com
Subject: Re: local selectivity estimation - computing frequency of predicates
In-Reply-To: <18791.1176473594@sss.pgh.pa.us>
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