Re: UPDATE SET (a,b,c) = (SELECT ...) versus rules

On Tue, Jun 17, 2014 at 9:02 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> But come to think of it, WITH is already an interesting precedent: if you
> look into rewriteHandler.c you'll notice a boatload of corner cases where
> the rewriter just throws up its hands for various combinations of rules
> and statements containing WITH.  So maybe that lends a bit more weight
> to Andres' position that it's okay to consider this an unimplemented
> feature.

This reflects previous consensus AIUI.  RULES came up in similar way
with the 'data modifying with' feature; it was decided that as long as
old stuff didn't break new features don't necessarily have to go
through the motions.  This essentially deprecates rules IMO, which is
fine.  Maybe a small adjustment of the note in the rule documentation
couldn't hurt; it currently warns based on performance...a heads up
that current and future SQL features might not be fully supported
would be nice.

merlin