Re: Status of FDW pushdowns

Hi Merlin,

2013/11/22 Merlin Moncure <mmoncure(at)gmail(dot)com>:
> On Thu, Nov 21, 2013 at 6:43 PM, Shigeru Hanada
> <shigeru(dot)hanada(at)gmail(dot)com> wrote:
>> 2013/11/22 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>>> Merlin Moncure <mmoncure(at)gmail(dot)com> writes:
>>>> On Thu, Nov 21, 2013 at 9:05 AM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>>>>> I know join pushdowns seem insignificant, but it helps to restrict what
>>>>> data must be passed back because you would only pass back joined rows.
>>>
>>>> By 'insignificant' you mean 'necessary to do any non-trivial real
>>>> work'. Personally, I'd prefer it if FDW was extended to allow
>>>> arbitrary parameterized queries like every other database connectivity
>>>> API ever made ever.
>>>
>>> [ shrug... ] So use dblink. For better or worse, the FDW stuff is
>>> following the SQL standard's SQL/MED design, which does not do it
>>> like that.
>>
>> Pass-through mode mentioned in SQL/MED standard might be what he wants.
>
> happen to have a link handy?

SQL/MED standard doesn't say much about PASS THROUGH mode, especially
about interaction between client. Besides it, I think it would be
nice to allow arbitrary FDW as backend of dblink interface like this:

postgres=> SELECT dblink_connect('con1', 'server name of an FDW');
postgres=> SELECT * FROM dblink('con1', 'some query written in remote
syntax') as t(/* record type definition */...);

This provides a way to execute query without defining foreign table.
--
Shigeru HANADA