2015-07-09 22:34 GMT+02:00 Nicolas Paris <nipari...@gmail.com>: > 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.
-- Guillaume. http://blog.guillaume.lelarge.info http://www.dalibo.com
