Hi, On 2019/04/20 20:53, Laurenz Albe wrote: > On Fri, 2018-04-06 at 23:24 +0000, Robert Haas wrote: >> Allow insert and update tuple routing and COPY for foreign tables. >> >> Also enable this for postgres_fdw. >> >> Etsuro Fujita, based on an earlier patch by Amit Langote. The larger >> patch series of which this is a part has been reviewed by Amit >> Langote, David Fetter, Maksim Milyutin, Álvaro Herrera, Stephen Frost, >> and me. Minor documentation changes to the final version by me. >> >> Discussion: >> http://postgr.es/m/29906a26-da12-8c86-4fb9-d8f88442f...@lab.ntt.co.jp > > This commit makes life hard for foreign data wrappers that support > data modifications. > > If a FDW implements ExecForeignInsert, this commit automatically assumes > that it also supports COPY FROM. It will call ExecForeignInsert without > calling PlanForeignModify and BeginForeignModify, and a FDW that does not > expect that will probably fail. > > So this commit silently turns a functioning FDW into a broken FDW. > That is not nice. Probably not every FDW is aware of this change, and > maybe there are FDWs that support INSERT but don't want to support COPY > for some reason.
That seems like an oversight to me. I agree that we had better checked that a table's FDW provides BeginForeignInsert() before proceeding with copying into the table, as your patch teaches CopyFrom() to do. > I propose that PostgreSQL only allows COPY FROM on a foreign table if the FDW > implements BeginForeignInsert. The attached patch implements that. Looks good to me, including the documentation change. > I think this should be backpatched to v11. Agreed. Thanks, Amit
