Re: Explain and filter over subplans

Thank you very much for your quick answer and patch!

I tested and this is exactly what I was looking for :-)

Best
Chantal

Le 18/01/2024 à 18:55, Tom Lane a écrit :
> Chantal Keller <chantal(dot)keller(at)universite-paris-saclay(dot)fr> writes:
>> I would like "explain" to output formulas for filtering over
>> subplans. Is it possible?
>
> No, and that's been a to-do item for a long time.
>
> Currently, EXPLAIN just ignores the "testexpr" field of SubPlan
> nodes, which is what you are after. We could print it, if we
> could figure out an intelligible representation. In the example
> you give, the testexpr would probably render as "t.a >= $0"
> where $0 represents the subplan's output column.
>
> A very rough sketch, perhaps, is that instead of just
> "(SubPlan 1)", we could print "(ALL t.a >= $0 FROM SubPlan 1)".
> Some of the other SubLinkTypes might be harder to represent
> in a way that makes sense to users.
>
> I made a quick-hack patch to play with, if you're interested.
>
> regards, tom lane
>