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mmkrishna1919
Yak Posting Veteran
95 Posts |
 Posted - 2012-08-23 : 05:54:26
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| Hi All,Below is Part of my execution plan in general terms:The below three operators are top inputs to the hash match/left outer join operatorTop1: Table1.primarykey col(non clustered index scan) cost 0% "ESTIMATED ROW COUNT 62952" TOP2.parallisum/repartition streams [partition columns table1.join column) "ESTIMATED ROW COUNT 62952"TOP3.bitmap/bitmapcreate[hash[table1.join col] "ESTIMATED ROW COUNT 62952"The below two operators are bottom inputs to the match/left outer joinBOTTOM1.table2.primarykey col(non clustered index scan) cost 0% "ESTIMATED ROW COUNT 1049585" BOTTOM2.parallisum/repartition streams [partition columns table1.join column) "ESTIMATED ROW COUNT 1049585"Argument here is:partition columns(table2.join col) where probe(bitmap(1004)=true)Now these two paths(top and bottom) are input to hash match/left outer join operator.Bitmap filter was created in "top3 step" on dimension table join column.And in "bottom2 step" the parallisum operator in this step if we look at the argument we can able to see bitmap filtering was done on fact table.From Botoom1 step(Table1.Pk_key) to bottom2 step(parallisum operator)The "ESTIMATED ROW COUNT is 1049585" And from bottom2 step(parallisum operator) to Hash match/left outer join The "ESTIMATED ROW COUNT is 1049585" same My Question is if Bitmap filtering was done at the parallisum operator(we can clearly see from argument section in execution plan),The "ESTIMATED ROW COUNT from bottom2 step to Hash match/left outer join should be 62952.Because the Bitmap filtering should discard those primary key rows from fact table are not there in dimensional table.But "ESTIMATED ROW COUNT is 1049585.After hash match/left outer join the "ESTIMATED ROW COUNT is 62592.Plz suggest why the "ESTIMATED ROW COUNT is still 1049585 after performing bitmap filtering in parallisum operator(bottom2 step)Thanks..M.MURALI kRISHNA |
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Bitmap/Bitmap create show plan operator