"David Fetter" <da...@fetter.org> writes: > CREATE SEQUENCE my_seq; > WITH t AS (SELECT nextval('my_seq')) VALUES(1); > SELECT currval('my_seq');
> ERROR: currval of sequence "my_seq" is not yet defined in this session > What's happened is that the optimization didn't account for the idea that a > SELECT might have a side effect, and if we're going with the "CTEs execute > exactly once and (equivalent to) fully," this is a bug. The reason it's not a bug is that we have not adopted that position. There is a proposal to make it so for wCTEs, but that doesn't mean we should change the existing, documented and useful behavior of regular CTEs. (If you're wondering where it's documented, I cite section 7.8's statement that only as much of a CTE query is evaluated as is read by the parent query. The limiting case of that is no reference -> no rows read.) 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