Re: Push down more full joins in postgres_fdw

>
>> Sorry. I think the current version is better than previous one. The
>> term "subselect alias" is confusing in the previous version. In the
>> current version, "Get the relation and column alias for a given Var
>> node," we need to add word "identifiers" like "Get the relation and
>> column identifiers for a given Var node".
>
>
> OK, but one thing I'm concerned about is the term "relation alias" seems a
> bit confusing because we already used the term for the alias of the form
> "rN". To avoid that, how about saying "table alias", not "relation alias"?
> (in which case, the comment would be something like "Get the table and
> column identifiers for a given Var node".)

table will be misleading as subquery can represent a join and
corresponding alias would represent the join. Relation is better term.

>
>
>> If we deparse from and search into different objects, that's not very
>> maintainable code. Changes to any one of them require changes to the
>> other, thus creating avenues for bugs. Even if slighly expensive, we
>> should search into and deparse from the same targetlist.
>
>
> I don't think so; in the current version, we essentially deparse from and
> search into the same object, ie, foreignrel->reltarget->exprs, since the
> tlist created by build_tlist_to_deparse is build from the
> foreignrel->reltarget->exprs. Also, since it is just created for deparsing
> the relation as a subquery in deparseRangeTblRef and isn't stored into
> fpinfo or anywhere alse, we would need no concern about creating such
> avenues. IMO I think adding comments would be enough for this.

build_tlist_to_depase() calls pull_var_nodes() before creating the
tlist, whereas the code that searches does not do that. Code-wise
those are not the same things.

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company