Re: Implement targetlist SRFs using ROWS FROM() (was Changed SRF in targetlist handling)

Hi,

On 2017-01-18 08:43:24 -0500, Tom Lane wrote:
> I did a review pass over 0001 and 0002. I think the attached updated
> version is committable

Cool.

> ... except for one thing. The more I look at it,
> the more disturbed I am by the behavioral change shown in rangefuncs.out
> --- that's the SRF-in-one-arm-of-CASE issue. (The changes in tsrf.out
> are fine and as per agreement.) We touched lightly on that point far
> upthread, but didn't really resolve it. What's bothering me is that
> we're changing, silently, from a reasonably-intuitive behavior to a
> completely-not-intuitive one. Since we got a bug report for the previous
> less-than-intuitive behavior for such cases, it's inevitable that we'll
> get bug reports for this. I think it'd be far better to throw error for
> SRF-inside-a-CASE. If we don't, we certainly need to document this,
> and I'm not very sure how to explain it clearly.

I'm fine with leaving it as is in the patch, but I'm also fine with
changing things to ERROR. Personally I don't think it matters much, and
we can whack it back and forth as we want later. Thus I'm inclined to
commit it without erroring out; since presumably we'll take some time
deciding on what exactly we want to prohibit.

> Anyway, I've not done anything about that in the attached. What I did do:
>
> * Merge 0001 and 0002. I appreciate you having separated that for my
> review, but it doesn't make any sense to commit the parts of 0001 that
> you undid in 0002.

Right. I was suggesting upthread that we'd merge them before committing.

> * Obviously, ExecMakeFunctionResultSet can be greatly simplified now
> that it need not deal with hasSetArg cases.

Yea, I've cleaned it up in my 0003; where it would have started to error
out too (without an explicit check), because there's no set evaluating
function anymore besides ExecMakeFunctionResultSet.

> I saw you'd left that
> for later, which is mostly fine, but I did lobotomize it just enough
> to throw an error if it gets a set result from an argument. Without
> that, we wouldn't really be testing that the planner splits nested
> SRFs correctly.

Ok, that makes sense.

> * This bit in ExecProjectSRF was no good:
>
> + else if (IsA(gstate->arg, FuncExprState) &&
> + ((FuncExpr *) gstate->arg->expr)->funcretset)
>
> because FuncExprState is used for more node types than just FuncExpr;
> in particular this would fail (except perhaps by accident) for a
> set-returning OpExpr.

Argh. That should have been FunExprState->func->fn_retset. Anyway, your
approach works, too.

> * Update the user documentation (didn't address the CASE issue, though).

Cool.

Greetings,

Andres