Re: Index occupancy

"tschak" <jochen(dot)schlosser(at)gmail(dot)com> writes:
> I have a question concerning the size of an index...
> What I acually did was bulid a btree index on an smallint attribute
> within a table with 10^8 rows. The table itself is app. 10GB large and
> what I would like to have the smallest possible indeces. Unfortunately
> the current size is about 2GB per indexed column (8 columns are indexed
> in total) which is too large if the planner is supposed to choose a
> bitmap scan between all of the indices.

> So what I would like to know is the following:
> Is there an easy way to tell postgres to occupy the index pages up to
> 100 %?

No, but even if there were it wouldn't make much of a difference. The
minimum possible size of a PG index is about 16 bytes per entry, which
would still put you at 1.6Gb for that many rows.

regards, tom lane