Re: Incorrect information in src/backend/optimizer/README

> From: Tom Lane [mailto:tgl@sss.pgh.pa.us]

> "Etsuro Fujita" <fujita.etsuro@lab.ntt.co.jp> writes:
> > ISTM the README contains incorrect information and requires revision
> > to reflect the current code.  Please find attached a patch.  ISTM the
> > patch needs to be applied to all active branches.
> 
> This patch isn't an improvement, since grouping_planner doesn't have anything
> to do with constant quals at all.  In modern releases, that's dealt with by
> create_gating_plan inside create_plan().

OK

> I remember looking at this text when I redid query_planner's API a few days
> ago and electing not to change it just then.  I'm a bit inclined to just
remove
> both references to constant quals from this overview, since they're now taken
> care of at much lower levels --- query_planner itself has nothing to do with
> that processing.  Alternatively, if we do want to discuss constant quals
> somewhere in here, maybe it needs to be in a separate subsection.  I'm not
sure
> we need anything though.  Constant quals are now handled just like other quals
> up till the last moment in createplan.c, where they're split out and put in
> a separate gating Result node just above where they would otherwise have been.

+1 for removing both of the references from the overview.

Thanks,

Best regards,
Etsuro Fujita