Alex Mayrhofer <axelm@nona.net> writes:
> a recent REINDEX reduced that index from about 30000 pages to 18000.
That's not bloat, that's normal overhead. The traditional rule of thumb
for a btree is that at steady state, pages will be about 2/3rds full.
REINDEX packs pages to 90% IIRC, but you can't expect that that density
will be maintained in the face of heavy update activity. It looks to me
like your index is not so far off the rule-of-thumb load factor, and you
should just not worry, be happy. If you were finding that your indexes
grow to ten times the minimum size, *that* would be worth worrying
about.
regards, tom lane