Re: Prove a NOT IN's left-hand expressions non-nullable from quals

HI

Thank you for updating the patch.
>
> One concern I had is the planning memory/time for nested joins. I may be
> missing something, but it seems that each node can copy and scan all
> accumulated descendant quals, potentially resulting in quadratic behavior.
> In my 160-join test, planning memory increased from 2.6 MB on master to 58
> MB with v2, even though no conversion was possible.
>
> Would it make sense, at minimum, to test the RHS first?
>
> if (under_not &&
> (!query_outputs_are_not_nullable(subselect) ||
> !sublink_testexpr_is_not_nullable(root, sublink, sqinfo)))
> return NULL;
>
> That would avoid unnecessary outer-side analysis when conversion is
> already impossible. However, unless I am overlooking something, the
> underlying quadratic behavior may still remain when conversions succeed.
>

Thanks