Hi all,
I was trying writing my own parallel aggregation functions on 9.6beta2.
During that, we found a bit confusing behavior with SAFE/UNSAFE options.
Once a PARALLEL UNSAFE function f1_unsafe() is wrapped by
a PARALLEL SAFE function f1_safe_unsafe(), calling f1_safe_unsafe()
produces a parallel execution plan despite it implicitly calls
the UNSAFE FUNCTION f1_unsafe().
Is this intentional?
Please take a look at our example here:
https://gist.github.com/snaga/362a965683fb2581bc693991b1fcf721
According to the manual[1], it is described as:
> the presence of such a function in an SQL statement forces a serial execution plan.
so, I expected that calling UNSAFE functions should produce
a non-parallel execution plan even wrapped in SAFE functions.
Is this a sort of limitations? Is this working correctly as we expected?
Regards,
[1] https://www.postgresql.org/docs/9.6/static/sql-createfunction.html
--
Satoshi Nagayasu <snaga@uptime.jp>