Query planning

From: Jayadevan M <maymala(dot)jayadevan(at)gmail(dot)com>
To: "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Query planning
Date: 2014-10-31 07:46:05
Message-ID: CAFS1N4gp-nJz63SrwiRruRUSOw9nYu8nEoTcXO+Ozc5joDx7hg@mail.gmail.com
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Hi all,

I am going through PostgreSQL documentation on how row estimation is done
in PostgreSQL.
http://www.postgresql.org/docs/current/static/row-estimation-examples.html
There is a reference to cardinality (rel_cardinality) there. But that is an
estimate of the number of rows in the table, right?

How many unique values are there in a column (cardinality), that is
estimated while finding out selectivity?

Regards,
Jayadevan

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