Re: Add semi-join pushdown to postgres_fdw

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.

-- 
Best regards,
Alexander Pyhalov,
Postgres Professional