Craig Ringer <craig@xxxxxxxxxxxxxxxxxxxxx> writes: > I'd already written: "If you need the test for status = 1, consider a > partial index" when I noticed your schema definition: >> "comments_created_by" btree (created_by) WHERE status = 1 > I find it hard to guess why it's having to recheck the WHERE clause > given the use of a partial index that should cover that nicely. No, that's operating as designed. A bitmap scan's RECHECK condition is only applied when the bitmap has become lossy due to memory pressure. In that case we have to look at each row on each of the pages fingered by the index as containing possible matches ... and we'd better check the partial-index qual too, since maybe not all the rows on those pages will satisfy it. In a plain indexscan there is no lossiness involved and so the partial-index qual need never be rechecked. regards, tom lane
