Hi all, It looks like Postgres has a restriction in DISTINCT ON queries where the DISTINCT ON expressions must match the left side of the ORDER BY list. The issue is that if a DISTINCT ON ... has multiple instances of a particular expression, this check doesn't seem to fire correctly.
For example, this query returns an error (but I guess it shouldn't): SELECT DISTINCT ON ('1'::varchar, '1'::varchar) a FROM (SELECT 1 AS a) AS a ORDER BY '1'::varchar, '1'::varchar, '2'::varchar; And this query doesn't return an error (but I guess it should): SELECT DISTINCT ON ('1'::varchar, '2'::varchar, '1'::varchar) a FROM (SELECT 1 AS a) AS a ORDER BY '1'::varchar, '2'::varchar, '2'::varchar; Am I misunderstanding something or is there a bug? Thanks for the help Emmanuel -- Emmanuel Cecchet Aster Data Web: http://www.asterdata.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers