"Maxim Boguk" <maxim(dot)boguk(at)gmail(dot)com> writes:
> Bug reference: 5328
> Logged by: Maxim Boguk
> Email address: maxim(dot)boguk(at)gmail(dot)com
> PostgreSQL version: 8.4.1
> Operating system: linux kernel v 2.6.18
> Description: GIN index with fastupdates=on provide wrong result on
> bitmap scan
The 8.4.2 release notes mention
* Fix wrong search results for a multi-column GIN index with fastupdate enabled (Teodor)
which seems to match your complaint. Please update and see if the
problem is resolved. You might need to reindex the GIN index after
updating to make things good.
regards, tom lane