I've been getting a funny SQL error, which I've boiled down to this case. SELECT (regexp_matches('abc', '(.)b(.)'))[1] IS NOT NULL -- Returns true, as expected SELECT (regexp_matches('abc', '(.)b(.)'))[1] IS NOT NULL AND true -- Gives this error: ERROR: argument of AND must not return a set SQL state: 42804 Can anyone make heads or tails of it? Is it a real bug? Is there a work around? Postgres 8.3 -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general