Re: Some problems regarding the self-join elimination code

On Fri, Apr 11, 2025 at 5:46 PM Andrei Lepikhov <lepihov(at)gmail(dot)com> wrote:
> On 4/10/25 14:39, Andrei Lepikhov wrote:
> > On 4/10/25 13:36, Alexander Korotkov wrote:
> >> On Wed, Apr 9, 2025 at 10:39 AM Andrei Lepikhov <lepihov(at)gmail(dot)com>
> >> wrote:
> >>> It seems we are coming to the conclusion that join removal optimisation
> >>> may do something out of ChangeVarNodes resposibility. Before further
> >>> complicating of this function code I would like to know opinion of Tom,
> >>> who initially proposed [1] to use this routine. May be better a) return
> >>> to more specialised change_relid / sje_walker machinery or b) move
> >>> ChangeVarNodes out of rewriteManip and make it multi-purpose routine,
> >>> allowing to transform expression that may happen after a Var node
> >>> change?
> >>
> >> What about adding a callback to ChangeVarNodes_context that would
> >> called for each RestrictInfo after changing varnodes itself? SJE
> >> could use a callback that replaces OpExpr with NullTest when needed.
> > I think it is doable, of course. Just looking forward a little, it may
> > need more complication in the future (SJE definitely should be widened
> > to partitioned tables) and it may be simpler to have two different
> > routines for two different stages of planning.
> To provide some food for thought, here is a draft in attachment which
> addresses both issues: RestrictInfo relid replacement and move
> SJE-specific code out of the ChangeVarNodes routine (callback approach).

Thank you, Andrei. I've put it all together.
0001 Fixes material bugs in ChangeVarNodes_walker() including regression test
0002 Puts back comments which got accidentally removed
0003 Refactors ChangeVarNodesExtended() with custom user-defined callback

I'm going to further work on improvement of these patches.

------
Regards,
Alexander Korotkov
Supabase