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: Dilip Kumar <dilipbalaut@gmail.com>, David Rowley <david.rowley@2ndquadrant.com>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>
Date: 2018-01-11T11:00:48Z
Lists: pgsql-hackers

Attachments

> On Thu, Dec 14, 2017 at 4:01 PM, Ashutosh Bapat <
> ashutosh.bapat@enterprisedb.com> wrote:
>
>>
>> +
>> +-- Partial aggregation as GROUP BY clause does not match with PARTITION
>> KEY
>> +EXPLAIN (COSTS OFF)
>> +SELECT b, sum(a), count(*) FROM pagg_tab GROUP BY b ORDER BY 1, 2, 3;
>> +                           QUERY PLAN
>> +----------------------------------------------------------------
>> + Sort
>> +   Sort Key: pagg_tab_p1.b, (sum(pagg_tab_p1.a)), (count(*))
>> +   ->  Finalize GroupAggregate
>> +         Group Key: pagg_tab_p1.b
>> +         ->  Sort
>> +               Sort Key: pagg_tab_p1.b
>> +               ->  Append
>> +                     ->  Partial HashAggregate
>> +                           Group Key: pagg_tab_p1.b
>> +                           ->  Seq Scan on pagg_tab_p1
>> +                     ->  Partial HashAggregate
>> +                           Group Key: pagg_tab_p2_s1.b
>> +                           ->  Append
>> +                                 ->  Seq Scan on pagg_tab_p2_s1
>> +                                 ->  Seq Scan on pagg_tab_p2_s2
>> +                     ->  Partial HashAggregate
>> +                           Group Key: pagg_tab_p3_s1.b
>> +                           ->  Append
>> +                                 ->  Seq Scan on pagg_tab_p3_s1
>> +                                 ->  Seq Scan on pagg_tab_p3_s2
>> +(20 rows)
>>
>> Why aren't we seeing partial aggregation paths for level two and below
>> partitions?
>>
>
>>
> In this version of the patch I have not recursed into next level.
> Will work on it and submit changes in the next patch-set.
>

 Attached new set of patches adding this. Only patch 0007 (main patch) and
0008 (testcase patch) has changed.

>
Please have a look and let me know if I missed any.

Thanks
-- 
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.