Tom Lane wrote:
I believe that the benefit of on-disk bitmap indexes is supposed to be reduced storage size (compared to btree).
I believe that the term "bitmap index" is also used with a different meaning wherein it actually does describe a particular kind of on-disk index structure, with one bit per table row.
IMHO building in-memory bitmaps (the first idea) is a very good idea to pursue for Postgres. I'm not at all sold on on-disk bitmap indexes, though ... those I suspect *are* sufficiently replaced by partial indexes.
In the cases where I have put them to use, they certainly occupy considerably less disk than a comparable btree index - provided there are not too many district values in the indexed column.
regards
Mark
---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
