Re: Can functions containing a CTE be PARALLEL SAFE? - Mailing list pgsql-general

From Tom Lane
Subject Re: Can functions containing a CTE be PARALLEL SAFE?
Date
Msg-id 19531.1571304003@sss.pgh.pa.us
Whole thread Raw
In response to Can functions containing a CTE be PARALLEL SAFE?  (Erwin Brandstetter <brsaweda@gmail.com>)
Responses Re: Can functions containing a CTE be PARALLEL SAFE?
List pgsql-general
Erwin Brandstetter <brsaweda@gmail.com> writes:
>> The following operations are always parallel restricted.
>> - Scans of common table expressions (CTEs).

> Now I am unsure whether I can use `PARALLEL SAFE` for functions containing
> a CTE (while  fulfilling all other criteria)?

AFAIR, the reason for treating CTEs as parallel restricted is simply to
guarantee single evaluation of the CTE.  Within a function, that would
only matter per-function-execution, so I can't see why a function
containing such a query couldn't be pushed down to workers for execution.

            regards, tom lane



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