On 05/04/2017 10:33 AM, Alvaro Herrera wrote: > I'm not sure what your point is. We know that for some cases the > optimization barrier semantics are useful, which is why the proposal is > to add a keyword to install one explicitely: > > with materialized r as > ( > select json_populate_record(null::mytype, myjson) as x > from mytable > ) > select (x).* > from r; > > this would preserve the current semantics.
I haven't been able to follow this incredibly long thread, so please excuse me if way off base, but are we talking about that a CTE would be silently be rewritten as an inline expression potentially unless it is decorated with some new syntax? I would find that very disconcerting myself. For example, would this CTE potentially get rewritten with multiple evaluation as follows? DROP SEQUENCE IF EXISTS foo_seq; CREATE SEQUENCE foo_seq; WITH a(f1) AS (SELECT nextval('foo_seq')) SELECT a.f1, a.f1 FROM a; f1 | ?column? ----+---------- 1 | 1 (1 row) ALTER SEQUENCE foo_seq RESTART; SELECT nextval('foo_seq'), nextval('foo_seq'); nextval | ?column? ---------+---------- 1 | 2 (1 row) Joe -- Crunchy Data - http://crunchydata.com PostgreSQL Support for Secure Enterprises Consulting, Training, & Open Source Development
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