Re: Two proposed modifications to the PostgreSQL FDW

(2018/08/21 16:03), Amit Langote wrote:
> On 2018/08/20 23:43, Tom Lane wrote:
>> Chris Travers<chris.travers@adjust.com>  writes:
>>> I am looking at trying to make two modifications to the PostgreSQL FDW and
>>> would like feedback on this before I do.
>>
>>> 1.  INSERTMETHOD=[insert|copy] option on foreign table.
>>
>>> One significant limitation of the PostgreSQL FDW is that it does a prepared
>>> statement insert on each row written which imposes a per-row latency.  This
>>> hits environments where there is significant latency or few latency
>>> guarantees particularly hard, for example, writing to a foreign table that
>>> might be physically located on another continent.  The idea is that
>>> INSERTMETHOD would default to insert and therefore have no changes but
>>> where needed people could specify COPY which would stream the data out.
>>> Updates would still be unaffected.

>> A different thing we could think about is enabling COPY TO/FROM a
>> foreign table.
>
> Fwiw, the following commit did introduce COPY FROM support for foreign
> tables, although using a FDW INSERT interface, so not exactly optimized
> for bulk-loading yet.
>
> commit 3d956d9562aa4811b5eaaaf5314d361c61be2ae0
> Author: Robert Haas<rhaas@postgresql.org>
> Date:   Fri Apr 6 19:16:11 2018 -0400
>
>      Allow insert and update tuple routing and COPY for foreign tables.

That's right.  To improve the efficiency, I plan to work on COPY FROM/TO 
a foreign table for PG12 (In [1], I proposed new FDW APIs for COPY FROM).

Sorry, I'm late to the party.

Best regards,
Etsuro Fujita

[1] 
https://www.postgresql.org/message-id/23990375-45a6-5823-b0aa-a6a7a6a957f0%40lab.ntt.co.jp