Re: assessing parallel-safety

On Tue, Mar 17, 2015 at 9:48 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Tue, Mar 17, 2015 at 2:26 AM, Noah Misch <noah@leadboat.com> wrote:
>> Neither that rule, nor its variant downthread, would hurt operator authors too
>> much.  To make the planner categorically parallel-safe, though, means limiting
>> evaluate_function() to parallel-safe functions.  That would dramatically slow
>> selected queries.  It's enough for the PL scenario if planning a parallel-safe
>> query is itself parallel-safe.  If the planner is parallel-unsafe when
>> planning a parallel-unsafe query, what would suffer?
>
> Good point.  So I guess the rule can be that planning a parallel-safe
> query should be parallel-safe.  From there, it follows that estimators
> for a parallel-safe operator must also be parallel-safe.  Which seems
> fine.

More work is needed here, but for now, here is a rebased patch, per
Amit's request.

--
Robert Haas
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