Re: Parallel Seq Scan

On Thu, Jul 16, 2015 at 1:10 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> Thanks, I will fix this in next version of patch.
>

I am posting in this thread as I am not sure, whether it needs a
separate thread or not?

I gone through the code and found that the newly added funnel node is
is tightly coupled with
partial seq scan, in order to add many more parallel plans along with
parallel seq scan,
we need to remove the integration of this node with partial seq scan.

To achieve the same, I have the following ideas.

Plan:
1) Add the funnel path immediately for every parallel path similar to
the current parallel seq scan,
but during the plan generation generate the funnel plan only for the
top funnel path and
ignore rest funnel paths.

2)Instead of adding a funnel path immediately after the partial seq
scan path is generated.
Add the funnel path in grouping_planner once the final rel path is
generated before creating the plan.

Execution:
The funnel execution varies based on the below plan node.
1) partial scan - Funnel does the local scan also and returns the tuples
2) partial agg - Funnel does the merging of aggregate results and
returns the final result.

Any other better ideas to achieve the same?

Regards,
Hari Babu
Fujitsu Australia