Marko Tiikkaja <marko.tiikkaja@cs.helsinki.fi> writes:
> Tom Lane wrote:
>> This doesn't really seem like a good idea from here. You're changing
>> a decision that has something like twenty years' standing in the code,
>> for no real gain. AFAICS this is just going to move the special cases
>> from point A to point B.
> Right, but this way you only have to special-case in grouping_planner(),
> and targetList always means the same thing.
If you think that, it just means you have not found all the places you
need to special-case ;-). One really obvious example is ruleutils.c,
and I rather imagine there are multiple places in the parser and
rewriter that would need attention, quite aside from whatever it does
to the planner.
If there were a clear net benefit, I'd be for changing, but I think
it's going to end up being roughly a wash. And if it's a wash we
should not change it, because when you consider the follow-on costs
(patches not back-patching, third-party code breaking, etc) that
means we'd come out way behind.
regards, tom lane