Re: Representing a SRF return column in catalogs

On Fri, Nov 7, 2014 at 7:15 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Wed, Nov 5, 2014 at 8:24 AM, Atri Sharma <atri(dot)jiit(at)gmail(dot)com> wrote:
> > I am working on something that requires representing a SRF return column
> in
> > pg_proc and being able to retrieve it, retrieve the name of the column
> and
> > make a ColumnRef node from it.
> >
> > The catch here are aliases:
> >
> > SELECT generate_series(1,100) AS a ORDER BY a;
> >
> > I need to know that the return column of generate_series is being
> referred
> > as a in this query (hence tlist, sortClause will have 'c').
> >
> > I discussed and think that a way can be to have position of column rather
> > than the actual name but that raises the question of the functionality
> > needed for back resolving position to name (to make a ColumnRef node) and
> > then infer that the column is being referred as an alias in this query.
>
> It's not clear to me what you are trying to do, so I can't give you any
> advice.

Let me give an example:

Consider an user defined SRF (or an inbuilt one (generate_series)). I am
working on a path keys tracking project (more details on it in a separate
email). I am interested in one of the columns of the result of the SRF and
want to store it in catalogs in a manner that allows me to refer it later
when executing the SRF.

One way can be to store the raw column name. However, I am not sure how
will that work around aliases without a considerable fiddling with Alias
nodes in parsetime.

Can I store relattnos or something? I need to get the stored att in planner
and build pathkeys from it.

Please advice.

Regards,

Atri

--
Regards,

Atri
*l'apprenant*