"Jens-Wolfhard Schicke" <j(dot)schicke(at)asco(dot)de> writes:
> I an explain analyze I saw recently, a BitmapOr node of 5 Bitmap Index Scan
> looked like this:
> BitmapOr (cost=43.57..43.57 rows=1833 width=0) (actual time=0.146..0.146
> rows=0 loops=1)
BitmapOr and BitmapAnd don't attempt to count their result rows --- doing
so would involve an extra scan over the bitmap, and what would you do
for lossy pages?
regards, tom lane