Re: Slow count(*) again... - Mailing list pgsql-performance

From bricklen
Subject Re: Slow count(*) again...
Date
Msg-id AANLkTimXSWapozrZNdiRXDSm2hdsha1As94NwuS967As@mail.gmail.com
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In response to Slow count(*) again...  (Neil Whelchel <neil.whelchel@gmail.com>)
Responses Re: Slow count(*) again...
List pgsql-performance
On Sat, Oct 9, 2010 at 4:26 PM, Neil Whelchel <neil.whelchel@gmail.com> wrote:
> Maybe an
> estimate(*) that works like count but gives an answer from the index without
> checking visibility? I am sure that this would be good enough to make a page
> list, it is really no big deal if it errors on the positive side, maybe the
> list of pages has an extra page off the end. I can live with that. What I
> can't live with is taking 13 seconds to get a page of results from 850,000
> rows in a table.
> -Neil-
>

FWIW, Michael Fuhr wrote a small function to parse the EXPLAIN plan a
few years ago and it works pretty well assuming your stats are up to
date.

http://markmail.org/message/gknqthlwry2eoqey

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