On Thu, May 26, 2016 at 4:25 AM, Etsuro Fujita <fujita.ets...@lab.ntt.co.jp> wrote: > On 2016/05/18 7:08, Michael Paquier wrote: >> >> On Wed, May 18, 2016 at 6:00 AM, Manuel Kniep <m.kn...@web.de> wrote: >>> >>> I realized that inserts into foreign tables are only done row by row. >>> Consider copying data from one local table to a foreign table with >>> >>> INSERT INTO foreign_table(a,b,c) SELECT a,b,c FROM local_table; >>> >>> When the foreign server is for example in another datacenter with long >>> latency, >>> this as an enormous performance trade off. > > >> I am adding Fujita-san in the loop here, he is >> quite involved with postgres_fdw these days so perhaps he has some >> input to offer. > > > Honestly, I didn't have any idea for executing such an insert efficiently, > but I was thinking to execute an insert into a foreign table efficiently, by > sending the whole insert to the remote server, if possible. For example, if > the insert is of the form: > > INSERT INTO foreign_table(a,b,c) VALUES (1, 2, 3), (4, 5, 6) or > INSERT INTO foreign_table(a,b,c) SELECT a,b,c FROM foreign_table2 > > where foreign_table and foreign_table2 belong to the same foreign server, > then we could send the whole insert to the remote server. > > Wouldn't that make sense?
Query strings have a limited length, and this assumption is true for many code paths in the backend code, so doing that with a long string would introduce more pain in the logic than anything else, as this would become more data type sensitive. -- Michael -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers