Re: Index oddity
От | Rod Taylor |
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Тема | Re: Index oddity |
Дата | |
Msg-id | 1086811930.2539.90.camel@jester обсуждение исходный текст |
Ответ на | Index oddity (ken <southerland@samsixedd.com>) |
Ответы |
Re: Index oddity
|
Список | pgsql-performance |
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 <table> ALTER COLUMN diagonalsize SET STATISTICS 1000; ANALZYE <table>; 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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