2021年3月30日(火) 2:54 Fujii Masao <masao.fu...@oss.nttdata.com>: > > On 2021/03/29 13:55, Michael Paquier wrote: > > On Mon, Mar 29, 2021 at 10:53:14AM +0900, Fujii Masao wrote: > >> I understand the motivation of this. But the other DMLs like UPDATE also > >> do the same thing for foreign tables? That is, when those DML commands > >> are executed on foreign tables, their changes are WAL-logged in a > >> publisher side, > >> e.g., for logical replication? If not, it seems strange to allow only > >> TRUNCATE > >> on foreign tables to be WAL-logged in a publisher side... > > > > Executing DMLs on foreign tables does not generate any WAL AFAIK with > > the backend core code, even with wal_level = logical, as the DML is > > executed within the FDW callback (see just ExecUpdate() or > > ExecInsert() in nodeModifyTable.c), and foreign tables don't have an > > AM set as they have no physical storage. A FDW may decide to generate > > some WAL records by itself though when doing the opeation, using the > > generic WAL interface but that's rather limited. > > > > Generating WAL for the truncation of foreign tables sounds also like a > > strange concept to me. I think that you should just make the patch > > work so as the truncation is passed down to the FDW that decides what > > it needs to do with it, and do nothing more than that. > > Agreed. > Ok, it's fair enough.
Best regards, -- HeteroDB, Inc / The PG-Strom Project KaiGai Kohei <kai...@heterodb.com>
