On 10/11/24 04:08, Koen De Groote wrote:
In the release notes for postgres 17 I'm reading:
> The PostgreSQL foreign data wrapper (postgres_fdw), used to execute
queries on remote PostgreSQL instances, can now push EXISTS and IN
subqueries to the remote server for more efficient processing.
I'm confused as to what this means. In older versions, are parts of
queries not sent to the foreign server? Or is this change meant to imply
the sending of only the subqueries, the result of which is then directly
used in pushing the entire query?
Or am I still wrong as to what this means?
I looked at the documentation and there doesn't seem to be any
indication of particular queries not being pushed to the foreign server,
so this wording that "can now push EXISTS and IN subqueries to the
remote server" is confusing.
What am I missing?
Read:
https://www.postgresql.org/docs/current/postgres-fdw.html#POSTGRES-FDW-REMOTE-QUERY-OPTIMIZATION
F.36.5. Remote Query Optimization
As to the change in the Release Note see the --hackers discussion:
https://www.postgresql.org/message-id/c9e2a757cf3ac2333714eaf83a9cc184%40postgrespro.ru
Regards,
Koen De Groote
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
