Re: Index oddity

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От
Rod Taylor
Тема
Re: Index oddity
Дата
Msg-id
1086811930.2539.90.camel@jester
Ответ на
Index oddity (ken)
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Index oddity ken <southerland@samsixedd.com>
Re: Index oddity Rod Taylor <pg@rbt.ca>
Re: Index oddity ken <southerland@samsixedd.com>
Re: Index oddity Rod Taylor <pg@rbt.ca>
Re: Index oddity ken <southerland@samsixedd.com>
Re: Index oddity Rod Taylor <pg@rbt.ca>
Re: Index oddity ken <southerland@samsixedd.com>
Re: Index oddity Christopher Kings-Lynne <chriskl@familyhealth.com.au>
Re: Index oddity Rod Taylor <pg@rbt.ca>
Re: Index oddity Mark Kirkwood <markir@coretech.co.nz>
Re: Index oddity "Joshua D. Drake" <jd@commandprompt.com>
Re: Index oddity Tom Lane <tgl@sss.pgh.pa.us>
Re: Index oddity (still) ken <southerland@samsixedd.com>
Re: Index oddity (still) Tom Lane <tgl@sss.pgh.pa.us> 
It seems to believe that the number of rows returned for the >49.999
case will be 4 times the number for the >50 case. If that was true, then
the sequential scan would be correct.

ALTER TABLE  ALTER COLUMN diagonalsize SET STATISTICS 1000;
ANALZYE 
;

Send back EXPLAIN ANALYZE output for the >49.999 case.

> The query plan for diagonalSize > 50.000 is ...
> 
> Index Scan using nrgfeature_xys_index on nrgfeature f 
> (cost=0.00..17395.79 rows=4618 width=220)
>    Index Cond: ((upperrightx > 321264.236977215::double precision) AND
> (lowerleftx < 324046.799812083::double precision) AND (upperrighty >
> 123286.261898636::double precision) AND (lowerlefty <
> 124985.927450476::double precision) AND (diagonalsize > 50::double
> precision))
> 
> ... while for diagonalSize > 49.999 is ...
> 
>  Seq Scan on nrgfeature f  (cost=0.00..31954.70 rows=18732 width=220)
>    Filter: ((upperrightx > 321264.236977215::double precision) AND
> (lowerleftx < 324046.799812083::double precision) AND (upperrighty >
> 123286.261898636::double precision) AND (lowerlefty <
> 124985.927450476::double precision) AND (diagonalsize > 49.999::double
> precision))
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