Re: Keep notnullattrs in RelOptInfo (Was part of UniqueKey patch series)

On Thu, Feb 11, 2021 at 8:22 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> writes:
> > Can this information be part of PathTarget structure and hence part of
> > RelOptInfo::reltarget, so that it can be extended to join, group and
> > other kinds of RelOptInfo in future?
>
> Why would that be better than keeping it in RelOptInfo?
>
>                         regards, tom lane

We have all the expressions relevant to a given relation (simple,
join, group whatever) in Pathtarget. We could remember notnullness of
attributes of a simple relation in RelOptInfo. But IMO non/nullness of
the TLEs of a relation is more useful that attributes and thus
associate those in the PathTarget which is used to produce TLEs. That
way we could use this infra in more general ways.

-- 
Best Wishes,
Ashutosh Bapat