Re: A performance issue with Memoize

On Fri, Oct 20, 2023 at 6:40 PM Richard Guo <guofenglinux(at)gmail(dot)com> wrote:

> I haven't thought thoroughly about the fix yet. But one way I'm
> thinking is that in create_subqueryscan_plan() we can first add the
> subquery's subplan_params to root->curOuterParams, and then replace
> outer-relation Vars in scan_clauses afterwards. That can make us be
> able to share the same PARAM_EXEC slot for the same Var that both
> belongs to the subquery's uplevel vars and to the NestLoop's
> outer-relation vars. To be concrete, something like attached.
>

After some more thought, I think this is the right way to fix this
issue. The idea here is to make sure that the same NLP Var shares the
same PARAM_EXEC slot. This change can also help to save PARAM_EXEC
slots (which is trivial though since slots are very cheap).

Thanks
Richard