> But is it? Is it impossible for the BRIN bitmap index scan to return 0 rows > (say, if the value being matched is outside the min/max boundary for every > block range?) Granted, if we document that it always returns 0 and should be > ignored, then confusing the actual 0 with the 0 as a representation of > “unknown” would be less a problem.
How about -1 ? It is an impossible value for sure. Maybe we should change BitmapAnd and BitmapOr nodes, too. It is better to make it obvious that it is not the correct value. I don't think many people would notice the note on the documentation. On the other hand, returning -1 broke parser of explain.depesz.com .  http://explain.depesz.com/s/tAkd -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers