Re: Order by (for 15 rows) adds 30 seconds to query time

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Kevin Grittner
Тема
Re: Order by (for 15 rows) adds 30 seconds to query time
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4B1522CE020000250002CEB1@gw.wicourts.gov
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Order by (for 15 rows) adds 30 seconds to query time Richard Neill <rn214@cam.ac.uk>
Re: Order by (for 15 rows) adds 30 seconds to query time Jean-Michel Pouré <jmpoure@free.fr>
Re: Order by (for 15 rows) adds 30 seconds to query time Richard Neill <rn214@cam.ac.uk>
Re: Order by (for 15 rows) adds 30 seconds to query time "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Re: Order by (for 15 rows) adds 30 seconds to query time Richard Neill <rn214@cam.ac.uk>
Re: Order by (for 15 rows) adds 30 seconds to query time Matthew Wakeling <matthew@flymine.org>
Re: Order by (for 15 rows) adds 30 seconds to query time Craig Ringer <craig@postnewspapers.com.au>
Re: Order by (for 15 rows) adds 30 seconds to query time "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Re: Order by (for 15 rows) adds 30 seconds to query time Tom Lane <tgl@sss.pgh.pa.us>
Re: Order by (for 15 rows) adds 30 seconds to query time "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Re: Order by (for 15 rows) adds 30 seconds to query time Tom Lane <tgl@sss.pgh.pa.us>
Re: Order by (for 15 rows) adds 30 seconds to query time "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Re: Order by (for 15 rows) adds 30 seconds to query time Richard Neill <rn214@cam.ac.uk>
Re: Order by (for 15 rows) adds 30 seconds to query time "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Re: Order by (for 15 rows) adds 30 seconds to query time Richard Neill <rn214@cam.ac.uk>
Re: Order by (for 15 rows) adds 30 seconds to query time "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
Richard Neill  wrote:
 
> I'd expect the ORDER BY to be the last thing that runs
 
>   Nested Loop Left Join  (cost=0.00..727737158.77
> rows=806903677108 width=195) (actual time=31739.052..32862.322
> rows=15 loops=1)
 
It probably would if it knew there were going to be 15 rows to sort.
It is estimating that there will be 806,903,677,108 rows, in which
case it thinks that using the index will be faster.  The question is
why it's 10 or 11 orders of magnitude off on the estimate of result
rows.  Could you show us the table definitions underlying that view?
 
-Kevin
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