BUG #5784: CREATE INDEX USING GIN complains about array containing null values yet none exist

The following bug has been logged online:

Bug reference:      5784
Logged by:          Martin Atukunda
Email address:      matlads@gmail.com
PostgreSQL version: 8.4
Operating system:   Linux
Description:        CREATE INDEX USING GIN complains about array containing
null values yet none exist
Details:

CREATE INDEX USING GIN complains about array containing null values yet none
exist.

Take the following SQL as an example.

-- >8 --

BEGIN;
CREATE TABLE t (id serial primary key, apps bigint[]);
INSERT INTO t (apps) VALUES ('{1,2,3,4}');
INSERT INTO t (apps) VALUES ('{1,2,3,4}');

-- insert an array with one element as a null value
INSERT INTO t (apps) VALUES ('{1,2,3,NULL}');

-- remove the null value
UPDATE t SET apps[4] = -1 WHERE apps[4] IS NULL;

-- the create index fails
CREATE INDEX  t_apps_idx ON t USING GIN(apps);

COMMIT;

-- 8< --


note that index creatiion succeeds if I first create the index without
inserting a row containing an array with a null element.

- Martin -