Hello philippe, not so easy to guess, the plan use randomly one of them ...
PLAN (HASH INDEX (HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_IDX, HASH_X1_Y5_IDX)) replacing the last HASH_X1_Y5_IDX by HASH_X1_Y2_IDX or HASH_X1_Y3_IDX or .. gave "around" the same result in speed even replacing it by all the index at the same time : HASH_X1_Y1_IDX, HASH_X1_Y2_IDX, HASH_X1_Y3_IDX, HASH_X1_Y4_IDX, HASH_X1_Y5_IDX the speed stay around the same ... also i not really understand why i need an index on CREATE ASC INDEX HASH_IDX ON HASH (X1_Y1, X1_Y2, X1_Y3, X1_Y4, X1_Y5); instead of just on CREATE ASC INDEX HASH_IDX ON HASH (X1_Y1, X1_Y2); (ie: trying to understand http://explainextended.com/2010/05/19/things-sql-needs-determining-range-cardinality/ ) thanks for all ! stéphane On 2/1/2012 3:10 PM, philippe makowski wrote: > > Vander Clock Stephane [2012-01-31 16:30] : > > now with this strategy i don't remenbered, but did i need to keep the > > index > > CREATE INDEX HASH_X1_Y1_IDX ON HASH (X1_Y1); > > CREATE INDEX HASH_X1_Y2_IDX ON HASH (X1_Y2); > > CREATE INDEX HASH_X1_Y3_IDX ON HASH (X1_Y3); > > CREATE INDEX HASH_X1_Y4_IDX ON HASH (X1_Y4); > > CREATE INDEX HASH_X1_Y5_IDX ON HASH (X1_Y5); > > > > or i can remove them ? > watch the PLAN, and you'll have the answer I guess > > [Non-text portions of this message have been removed]
