Horton

Re: Partition-wise aggregation/grouping

Antonin Houska <ah@cybertec.at>

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From: Antonin Houska <ah@cybertec.at>
To: pgsql-hackers@postgresql.org
Date: 2017-04-05T08:46:51Z
Lists: pgsql-hackers 
Antonin Houska <ah@cybertec.at> wrote:
> 
> Jeevan Chalke <jeevan.chalke@enterprisedb.com> wrote:
> 
> > Our work will overlap when we are pushing down the aggregate on partitioned
> > base relation to its children/partitions.
> > 
> > I think you should continue working on pushing down aggregate onto the
> > joins/scans where as I will continue my work on pushing down aggregates to
> > partitions (joins as well as single table). Once we are done with these task,
> > then we may need to find a way to integrate them.
> > 
> > [1] https://www.postgresql.org/message-id/flat/CAFjFpRfQ8GrQvzp3jA2wnLqrHmaXna-urjm_UY9BqXj=EaDTSA@mail.gmail.com#CAFjFpRfQ8GrQvzp3jA2wnLqrHmaXna-urjm_UY9BqXj=EaDTSA@mail.gmail.com
> 
> My patch does also create (partial) aggregation paths below the Append node,
> but only expects SeqScan as input. Please check if you patch can be based on
> this or if there's any conflict.

Well, I haven't imposed any explicit restriction on the kind of path to be
aggregated below the Append path. Maybe the only thing to do is to merge my
patch with the "partition-wise join" patch (which I haven't checked yet).

-- 
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at

Commits

  1. postgres_fdw: Push down partition-wise aggregation.

  2. Remove 'target' from GroupPathExtraData.

  3. Implement partition-wise grouping/aggregation.

  4. Don't pass the grouping target around unnecessarily.

  5. Determine grouping strategies in create_grouping_paths.

  6. Defer creation of partially-grouped relation until it's needed.

  7. Split create_grouping_paths into degenerate and non-degenerate cases.

  8. Pass additional arguments to a couple of grouping-related functions.

  9. Fix logic error in add_paths_to_partial_grouping_rel.

  10. Minor cleanup of code related to partially_grouped_rel.

  11. Add a new upper planner relation for partially-aggregated results.

  12. Charge cpu_tuple_cost * 0.5 for Append and MergeAppend nodes.

  13. Rename enable_partition_wise_join to enable_partitionwise_join

  14. Factor some code out of create_grouping_paths.

  15. Pad XLogReaderState's main_data buffer more aggressively.

  16. Prevent int128 from requiring more than MAXALIGN alignment.

  17. Fix DROP SUBSCRIPTION hang

  18. Inject $(ICU_LIBS) regardless of platform.

  19. Some preliminary refactoring towards partitionwise join.