Horton

Re: [HACKERS] Partition-wise aggregation/grouping

Jeevan Chalke <jeevan.chalke@enterprisedb.com>

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From: Jeevan Chalke <jeevan.chalke@enterprisedb.com>
To: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, David Rowley <david.rowley@2ndquadrant.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2018-03-13T14:13:05Z
Lists: pgsql-hackers

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Hi,

I have resolved all the comments/issues reported in this new patch-set.

Changes done by Ashutosh Bapat for splitting out create_grouping_paths()
into separate functions so that partitionwise aggregate code will use them
were based on my partitionwise aggregate changes. Those were like
refactoring changes. And thus, I have refactored them separately and before
any partitionwise changes (see
0005-Split-create_grouping_paths-and-Add-GroupPathExtraDa.patch). And then
I have re-based all partitionwise changes over it including all fixes.

The patch-set is complete now. But still, there is a scope of some comment
improvements due to all these refactorings. I will work on it. Also, need
to update few documentations and indentations etc. Will post those changes
in next patch-set. But meanwhile, this patch-set is ready to review.


On Tue, Mar 13, 2018 at 9:12 AM, Ashutosh Bapat <
ashutosh.bapat@enterprisedb.com> wrote:

> On Mon, Mar 12, 2018 at 7:49 PM, Jeevan Chalke
> <jeevan.chalke@enterprisedb.com> wrote:
> >
> >
> > On Mon, Mar 12, 2018 at 6:07 PM, Ashutosh Bapat
> > <ashutosh.bapat@enterprisedb.com> wrote:
> >>
> >> On Fri, Mar 9, 2018 at 4:21 PM, Ashutosh Bapat
> >>
> We don't need UpperRelationKind member in that structure. That will be
> provided by the RelOptInfo passed.
>
> The problem here is the extra information required for grouping is not
> going to be the same for that needed for window aggregate and
> certainly not for ordering. If we try to jam everything in the same
> structure, it will become large with many members useless for a given
> operation. A reader will not have an idea about which of them are
> useful and which of them are not. So, instead we should try some
> polymorphism. I think we can pass a void * to GetForeignUpperPaths()
> and corresponding FDW hook knows what to cast it to based on the
> UpperRelationKind passed.
>

Yep. Done this way.


>
> BTW, the patch has added an argument to GetForeignUpperPaths() but has
> not documented the change in API. If we go the route of polymorphism,
> we will need to document the mapping between UpperRelationKind and the
> type of structure passed in.
>

Oops. Will do that in next patchset.

Thanks for pointing out, I have missed this at first place it self.

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

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.