Re: inherit support for foreign tables

Sent from my iPad

On 28-Jan-2014, at 10:04, Kouhei Kaigai <kaigai@ak.jp.nec.com> wrote:

>>> I wonder what shall be the cases when foreign table is on a server which
>> does not support *all* SQL features.
>>>
>>> Does a FDW need to have the possible inherit options mentioned in its
>> documentation for this patch?
>>
>> The answer is no, in my understanding.  The altering operation simply
>> declares some chages for foreign tables in the inheritance tree and does
>> nothing to the underlying storages.
> It seems to me Atri mention about the idea to enforce constraint when
> partitioned foreign table was referenced...
>
> BTW, isn't it feasible to consign FDW drivers its decision?
> If a foreign table has a check constraint (X BETWEEN 101 AND 200),
> postgres_fdw will be capable to run this check on the remote server,
> however, file_fdw will not be capable. It is usual job of them when
> qualifiers are attached on Path node.
> Probably, things to do is simple. If the backend appends the configured
> check constraint as if a user-given qualifier, FDW driver will handle

Hi,

I think that pushing it to FDW driver is the best approach. The FDW driver knows whether or not the foreign server
supportsthe said feature,hence,the user should be abstracted from that. 

I agree that the foreign constraint can be added as a user defined qualifier and dealt with accordingly.

Regards,

Atri