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From Jayadevan M
Subject Query planning
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Msg-id CAFS1N4gp-nJz63SrwiRruRUSOw9nYu8nEoTcXO+Ozc5joDx7hg@mail.gmail.com
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Responses Re: Query planning  (Emanuel Calvo <emanuel.calvo@2ndquadrant.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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