Re: [HACKERS] Partition-wise aggregation/grouping

On Sat, Mar 3, 2018 at 12:12 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Thu, Mar 1, 2018 at 4:52 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > This is not a full review, but I'm out of time for right now.
>
> Another thing I see here now is that create_grouping_paths() and
> create_child_grouping_paths() are extremely similar. Isn't there some
> way we can refactor things so that we can reuse the code instead of
> duplicating it?
>

Yes. I too observed the same after our re-design.

To avoid code duplication, I am now calling create_grouping_paths() for
child relation too.

However, to perform Gather or Gather Merge once we have all partial paths
ready, and to avoid too many existing code rearrangement, I am calling
try_partitionwise_grouping() before we do any aggregation/grouping on whole
relation. By doing this, we will be having all partial paths in
partially_grouped_rel and then existing code will do required finalization
along with any Gather or Gather Merge, if required.

Please have a look over attached patch-set and let me know if it needs
further changes.

Thanks

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

--
Jeevan Chalke
Technical Architect, Product Development
EnterpriseDB Corporation
The Enterprise PostgreSQL Company