On Tue, Sep 08, 2009 at 11:37:14PM -0400, Tom Lane wrote: > I wrote: > > David Fetter <da...@fetter.org> writes: > >> WITH RECURSIVE t(j) AS ( > >> WITH RECURSIVE s(i) AS ( > >> VALUES (1) > >> UNION ALL > >> SELECT i+1 FROM s WHERE i < 10 > >> ) SELECT i AS j FROM s > >> UNION ALL > >> SELECT j+1 FROM t WHERE j < 10 > >> ) > >> SELECT * FROM t; > >> ERROR: relation "s" does not exist > >> LINE 6: ) SELECT i AS j FROM s > >> ^ > >> Shouldn't this work? > > > Huh, nice test case. It looks like it's trying to do the "throwaway > > parse analysis" of the nonrecursive term (around line 200 of > > parse_cte.c) without having analyzed the inner WITH clause. We could > > probably fix it by doing a throwaway analysis of the inner WITH too > > ... but ... that whole throwaway thing is pretty ugly and objectionable > > from a performance standpoint anyhow. I wonder if it wouldn't be better > > to refactor so that transformSetOperationStmt knows when it's dealing > > with the body of a recursive UNION and does the analyzeCTETargetList > > business after having processed the first UNION arm. > > I've committed a fix along those lines. Too late for 8.4.1 > unfortunately :-(. In the meantime, you could work around the > problem in this particular case with some more parentheses: > > WITH RECURSIVE t(j) AS ( > ( > WITH RECURSIVE s(i) AS ( > VALUES (1) > UNION ALL > SELECT i+1 FROM s WHERE i < 10 > ) SELECT i AS j FROM s > ) > UNION ALL > SELECT j+1 FROM t WHERE j < 10 > ) > SELECT * FROM t; > > regards, tom lane
I tested this with deeper-nested structures, and ran across another question: Should the outer query be able to reference further-in CTEs? WITH RECURSIVE s(i) AS ( WITH RECURSIVE t(j) AS ( VALUES(1) UNION ALL SELECT j+1 FROM t WHERE j < 10 ) SELECT j AS i FROM t UNION ALL SELECT i+1 FROM s WHERE i < 10 ) SELECT * FROM s,t; ERROR: relation "t" does not exist LINE 11: SELECT * FROM s,t; ^ Cheers, David. -- David Fetter <da...@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers