David Johnston <pol...@yahoo.com> writes: >> Here is a minimal query that demonstrates the problem. In 9.1 it works: >> >> chris=# select * FROM current_user u join (current_user u cross join >> current_user v) x on true; >> >> On 9.3 it fails: >> ERROR: table name "u" specified more than once
This is an intentional change that came in with the LATERAL feature. The query is illegal per SQL spec but we used to allow it anyway, on the theory that the table name "u" inside the aliased join "x" wasn't visible anywhere that the other "u" was visible, so the duplicate alias name was harmless. But in the presence of LATERAL it's not harmless; consider select * FROM current_user u join (current_user u cross join LATERAL (select u.x) v) x on true; Which instance of "u" does the lateral reference refer to? (I think there was some discussion of this in the pgsql-hackers list about a year ago, but I couldn't find it in a desultory search.) regards, tom lane -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs