Stefan Holzheu <stefan.holzheu@bayceer.uni-bayreuth.de> writes:
> Other queries with the equal operator do match rows. Am I missing something?
> Postgresql: 8.1.1
> Fieldtype: text
> Database encoding: Latin9
What LC_COLLATE locale are you using? Your report looks a whole lot
like the recently identified problem with locales that think that some
not-bitwise-identical strings are "equal", as in this thread:
http://archives.postgresql.org/pgsql-general/2005-12/msg00740.php
If the same queries return sane results after doing set enable_indexscan
= off, then that's probably what the problem is. If so, updating to
8.1.2 and REINDEXing should fix it.
regards, tom lane