The patch attached is based on the one rejected at the last CF for 9.0 last year.
http://archives.postgresql.org/message-id/16303.1266023...@sss.pgh.pa.us This patch implements the feature that allows top-level DMLs under CTE WITH clause. For example: WITH t AS (SELECT * FROM x) UPDATE y SET val = t.val FROM t WHERE y.key = t.key; This feature is part of writeable CTEs proposed by David Fetter originally. There were two issues at the CF. 1. WITH clause atop INSERT Although the previous discussion got the consensus that we forbid WITH atop INSERT, it seems to me that it can be allowed. I managed to do it by treating the top WITH clause (of INSERT) as if the one of SELECT (or VALUES). It is possible to disallow the CTE over INSERT statement, but the lack for INSERT, though there are for UPDATE and DELETE, sounds inconsistent enough. 2. OLD/NEW in rules Following the subsequent discussion after the post linked above, I add code to throw an appropriate error when OLD/NEW is used in WITH clauses. It is true that OLD/NEW references look sane to general users, but actually (at least in our implementation) they are located in the top-level query's Range Table List. Consequently, they are invisible inside the WITH clause. To allow them, we should rewrite the rule systems overall. Thus, we forbid them in WITH though we should throw an error indicating appropriate message. I'll add the entry to CF app later. Any feedback is welcome. Regards, -- Hitoshi Harada
toplevel-dml-cte.20100913.patch
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