The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/9.6/static/release-9-6.html
Description:
Hello everybody.
I have a doubt about parallel queries and writing operations.
According to
https://www.postgresql.org/docs/9.6/static/release-9-6.html#AEN130398
«Only strictly read-only queries where the driving table is accessed via a
sequential scan can be parallelized»
My question is: If a WITH clause contains only read operations, but its
results is used to feed a writing operation, like an insert or update, it is
not allowed to parallelize sequential scans?
For example:
WITH foobarbaz AS (
SELECT foo FROM bar
WHERE some_expensive_function(baz)
)
DELETE FROM bar
USING foobarbaz
WHERE bar.foo = foobarbaz.foo
;
Is that foobarbaz calculation expected to be parallelized or it is
disallowed because of the delete sentence?
Thanks in advance.
Regards.
--
Joanmi
