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Re: Column correlation drifts, index ignored again

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: siracusa(at)mindspring(dot)com
Cc: Postgres Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Column correlation drifts, index ignored again
Date: 2004-02-23 03:38:40
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
John Siracusa <siracusa(at)mindspring(dot)com> writes:
> Does the planner get estimates from both plans before deciding whether or
> not to use the one that references the date index?

The rowcount estimate is made prior to the plan cost estimate, much less
the plan selection.  So you'd see the same number either way.

			regards, tom lane

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