Re: struct RelOptInfo member relid comments

On Fri, May 24, 2024 at 9:09 AM jian he <jian(dot)universality(at)gmail(dot)com> wrote:

> On Fri, May 24, 2024 at 11:14 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
> > jian he <jian(dot)universality(at)gmail(dot)com> writes:
> > > imho, the above comment is not very helpful.
> > > we should say more about what kind of information relid says about a
> base rel?
> >
> > "Relid" is defined at the very top of the file:
> >
> > /*
> > * Relids
> > * Set of relation identifiers (indexes into the
> rangetable).
> > */
> > typedef Bitmapset *Relids;
> >
> > Repeating that everyplace the term "relid" appears would not be
> > tremendously helpful.
> >
>
> `Index relid;`
> is a relation identifier, a base rel's rangetable index.
>
> Does the above description make sense?
>
>
> BTW, I found several occurrences of "base+OJ", but I cannot find the
> explanation of "OJ" or the "OJ" Acronyms.
>
>
> OJ is an outer join, AFAIU. OJ's have their own relids. If you are
wondering why not all joins - I think inner joins need not be tracked as
separated relations in parse tree, but OJ's need to be.

--
Best Wishes,
Ashutosh Bapat