Thread: Parallel queries on CTE for writing operations.

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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