I took a quick look through this patch. While I see nothing to complain
about implementation-wise, I'm a bit befuddled as to why we need this
reporting when there is no comparable data provided for regular index-only
scans. Over there, you just get "Heap Fetches: n", and the existing
counts for bitmap scans seem to cover the same territory.
I agree with the original comment that it's pretty strange that
EXPLAIN doesn't identify an index-only BMS at all; but fixing that
is a different patch.
regards, tom lane
