Re: Add semi-join pushdown to postgres_fdw

Hi, Alexander!

On Mon, Nov 27, 2023 at 5:11 PM Alexander Pyhalov
<a(dot)pyhalov(at)postgrespro(dot)ru> wrote:
> Alexander Korotkov писал(а) 2023-11-27 03:49:
>
> > Thank you for the revision.
> >
> > I've revised the patch myself. I've replaced StringInfo with
> > additional conds into a list of strings as I proposed before. I think
> > the code became much clearer. Also, it gets rid of some unnecessary
> > allocations.
> >
> > I think the code itself is not in bad shape. But patch lacks some
> > high-level description of semi-joins processing as well as comments on
> > each manipulation with additional conds. Could you please add this?
> >
>
> Hi. The updated patch looks better. It seems I've failed to fix logic in
> deparseFromExprForRel() when tried to convert StringInfos to Lists.
>
> I've added some comments. The most complete description of how SEMI-JOIN
> is processed, is located in deparseFromExprForRel(). Unfortunately,
> there seems to be no single place, describing current JOIN deparsing
> logic.

Looks good to me. I've made some grammar and formatting adjustments.
Also, I've written the commit message.

Now, I think this looks good. I'm going to push this if no objections.

------
Regards,
Alexander Korotkov