Re: Is exec_simple_check_node still doing anything?

I wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> I'm a little mystified by exec_simple_check_node().
>> ...
>> Did that, possibly, remove the last way in which a simple expression
>> could be could become non-simple? If so, between that and the new
>> hasTargetSRFs test, it might now be impossible for
>> exec_simple_check_node() to fail.

> In fact, I suspect we could get rid of exec_simple_recheck_plan
> altogether. It could use a bit more study, but the empty-rtable
> check plus the other checks in exec_simple_check_plan (particularly,
> hasAggs, hasWindowFuncs, hasTargetSRFs, hasSubLinks) seem like
> they are enough to guarantee that what comes out of the planner
> will be "simple".

I did some more studying and it definitely seems like
exec_simple_recheck_plan can never fail anymore. As an experimental
check, converting everything it was testing into Asserts still gets
through check-world. Accordingly, here's a proposed patch that gets
rid of exec_simple_check_node() and simplifies some of the rest of
the logic.

regards, tom lane