Re: [HACKERS] why not parallel seq scan for slow functions

On Wed, Nov 8, 2017 at 7:26 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> We do want to generate it later when there isn't inheritance involved,
> but only if there is a single rel involved (simple_rel_array_size
> <=2).  The rule is something like this, we will generate the gather
> paths at this stage only if there are more than two rels involved and
> there isn't inheritance involved.

Why is that the correct rule?

Sorry if I'm being dense here.  I would have thought we'd want to skip
it for the topmost scan/join rel regardless of the presence or absence
of inheritance.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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