"Matt Smiley" <mss@xxxxxxxxxxx> writes: > So an Index Scan is always going to have a higher cost estimate than > an equivalent Seq Scan returning the same result rows (unless > random_page_cost is < 1). That's why I think the planner is always > preferring the plan that uses a Seq Scan. If that were the case, we'd never choose an indexscan at all... It's true that a plain indexscan is not preferred for queries that will return a large fraction of the table. However, it should be willing to use a bitmap scan for this query, given default cost settings (the default cost settings will cause it to prefer bitmap scan for retrieving up to about a third of the table, in my experience). I too am confused about why it doesn't prefer that choice in the OP's example. It would be interesting to alter the random_page_cost setting and see if he gets different results. regards, tom lane
