Jon Nelson <jnelson+pgsql(at)jamponi(dot)net> writes:
> CREATE INDEX foo_idx ON t USING GIN (alternatecodes) WHERE
> alternatecodes IS NOT NULL;
> SELECT * FROM t WHERE alternatecodes IS NOT NULL;
> ERROR: GIN indexes do not support whole-index scans
Yep, this is a known issue. It's going to take major surgery on GIN to
fix it, so don't hold your breath. In the particular case, what good do
you think the WHERE clause is doing anyway? GIN won't index nulls at
all ... which indeed is an aspect of the underlying issue --- see recent
discussions, eg here:
http://archives.postgresql.org/pgsql-hackers/2010-10/msg00521.php
regards, tom lane