Re: inherit support for foreign tables

(2014/07/01 15:13), Ashutosh Bapat wrote:
> On Tue, Jul 1, 2014 at 7:39 AM, Etsuro Fujita
> <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp <mailto:fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>> wrote:

> We may want to modify use_physical_tlist(), to return false, in case of
> foreign tables. BTW, it does return false for inheritance trees.

Yeah, but please consider cases where foreign tables are not inheritance
child rels (and any system columns are requested).

> 486 /*
> 487 * Can't do it with inheritance cases either (mainly because
> Append
> 488 * doesn't project).
> 489 */
> 490 if (rel->reloptkind != RELOPT_BASEREL)
> 491 return false;
>
> Yeah, we can call build_physical_tlist() (and do that in some
> cases), but if we call the function, it would generate a tlist that
> contains all Vars in the relation, not only those Vars actually
> needed by the query (ie, Vars in reltargetlist), and thus it would
> take more cycles to compute attr_used from the tlist than from
> reltargetlist. That' what I wanted to say.

Maybe I'm missing something, but what's the point of using the tlist,
not reltargetlist?

Thanks,

Best regards,
Etsuro Fujita