GIN overlap vs empty arrays - Mailing list pgsql-bugs

Ran into this and I'm trying to decide if this is functioning as
designed or if this is a bug that should be fixed: (PG 8.4.2)

create table gintest
(
    idList int[],
    foo text
);

create index gintest_gin_idx on gintest using gin(idList gin__int_ops);

insert into gintest(idlist, foo) values (array[1,2,3], 'bar');

select * from gintest where idList && array[]::int[];

CREATE TABLE
CREATE INDEX
INSERT 0 1
psql:ginproblem.sql:11: ERROR:  GIN indexes do not support whole-index
scans

I came across this in a production setting and widdled it down to
this.  In a nutshell using overlap with an empty (not null) array
causes this error.   Should there be a short circuit to bail on zero-
length input to overlap since you can't overlap with nothing.  (if you
pass in a plain null it works fine).

In the production setting it is tickled by the array being produced by
a subselect that uses array_accum to gather a list of ids to pull up.

If this is the proper behavior I'll deal with it (in the end the
result is the same - no rows).  Just a bit surprised by it.

--
Jeff Trout <jeff@jefftrout.com>
http://www.stuarthamm.net/
http://www.dellsmartexitin.com/