Re: Optimization for updating foreign tables in Postgres FDW

On Thu, Jan 28, 2016 at 11:33 AM, Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp
> wrote:

> On 2016/01/27 21:23, Rushabh Lathia wrote:
>
>> If I understood correctly, above documentation means, that if FDW have
>> DMLPushdown APIs that is enough. But in reality thats not the case, we
>> need ExecForeignInsert, ExecForeignUpdate, or ExecForeignDelete in case
>> DML is not pushable.
>>
>> And here fact is DMLPushdown APIs are optional for FDW, so that if FDW
>> don't have DMLPushdown APIs they can still very well perform the DML
>> operations using ExecForeignInsert, ExecForeignUpdate, or
>> ExecForeignDelete.
>>
>
> I agree with you. I guess I was wrong. sorry.
>
> So documentation should be like:
>>
>> If the IsForeignRelUpdatable pointer is set to NULL, foreign tables are
>> assumed to be insertable, updatable, or deletable if the FDW provides
>> ExecForeignInsert, ExecForeignUpdate, or ExecForeignDelete respectively,
>>
>> If FDW provides DMLPushdown APIs and the DML are pushable to the foreign
>> server, then FDW still needs ExecForeignInsert, ExecForeignUpdate, or
>> ExecForeignDelete for the non-pushable DML operation.
>>
>> What's your opinion ?
>>
>
> I agree that we should add this to the documentation, too.
>
> BTW, if I understand correctly, I think we should also modify
> relation_is_updatabale() accordingly. Am I right?
>

Yep, we need to modify relation_is_updatable().

>
> Best regards,
> Etsuro Fujita
>
>
>

--
Rushabh Lathia