Re: Parallel Seq Scan

On Thu, Nov 5, 2015 at 12:52 AM, Haribabu Kommi
<kommi(dot)haribabu(at)gmail(dot)com> wrote:
>> Now instead of displaying Partial Seq Scan, if we just display Seq Scan,
>> then it might confuse user, so it is better to add some thing indicating
>> parallel node if we want to go this route.
>
> IMO, the change from Partial Seq Scan to Seq Scan may not confuse user,
> if we clearly specify in the documentation that all plans under a Gather node
> are parallel plans.
>
> This is possible for the execution nodes that executes fully under a
> Gather node.
> The same is not possible for parallel aggregates, so we have to mention the
> aggregate node below Gather node as partial only.
>
> I feel this suggestion arises as may be because of some duplicate code between
> Partial Seq Scan and Seq scan. By using Seq Scan node only if we display as
> Partial Seq Scan by storing some flag in the plan? This avoids the
> need of adding
> new plan nodes.

I was thinking about this idea:

1. Add a parallel_aware flag to each plan.

2. If the flag is set, have EXPLAIN print the word "Parallel" before
the node name.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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