2015-07-09 22:34 GMT+02:00 Nicolas Paris <niparisco@xxxxxxxxx>:
Hello,My 9.4 database is used as datawharehouse. I can't change the queries generated.first index : INDEX COL (A,B,C,D,E)In case of query based on COL A, the query planner sometimes go to a seq scan instead of using the first composite index.The solution is to add a second indexe (redondant)second index : INDEX COL (A)In case of query based on COL A, B, C, D, (without E) as well, it doesn't uses the first index and prefers a seq scan.I could create a third indexe :first index : INDEX COL (A,B,C,D)But I hope there is an other solution for that (table is huge).It seems that the malus for using composite indexes is high.Question is : is there a way to make the composite index more attractive to query planner ? (idealy equivalent to mono column indexe)
There's no way we can answer that without seeing actual queries and query plans.
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