Re: Odd explain estimate

On Thu, Jul 31, 2003 at 05:59:59PM -0500, Jim C. Nasby wrote:
>
> Well, if I don't do this it wants to seqscan a table that occupies 350k
> pages, instead of pulling a couple thousand rows. I started running it
> with the seqscan and it's already taken way longer than it does if I
> disable seqscan.

That was indeed the question.

If it uses a seqscan when it ought not to do, then there's something
wrong with the statistics, or you haven't vacuum analysed correctly,
or your table needs vacuum full (is it really 350k pages, or is that
mostly dead space?), &c. -- all the usual bad-seqscan candidates.

enable_seqscan=off is probably not a good strategy for any moderately
complicated query. If the planner were perfect, of course, you'd
never need it at all.

A

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