Horton

Re: POC: GROUP BY optimization

Tomas Vondra <tomas.vondra@enterprisedb.com>

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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: "Jonathan S. Katz" <jkatz@postgresql.org>, David Rowley <dgrowleyml@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Zhihong Yu <zyu@yugabyte.com>, "Andrey V. Lepikhov" <a.lepikhov@postgrespro.ru>, Teodor Sigaev <teodor@sigaev.ru>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2022-09-04T22:14:48Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Restore preprocess_groupclause()

  2. Rename PathKeyInfo to GroupByOrdering

  3. Add invariants check to get_useful_group_keys_orderings()

  4. Fix asymmetry in setting EquivalenceClass.ec_sortref

  5. Multiple revisions to the GROUP BY reordering tests

  6. Get rid of pg_class usage in SJE regression tests

  7. Rename index "abc" in aggregates.sql

  8. Explore alternative orderings of group-by pathkeys during optimization.

  9. Generalize the common code of adding sort before processing of grouping

  10. Fix out-dated comment in preprocess_groupclause()

  11. Force parallelism in partition_aggregate

  12. Optimize order of GROUP BY keys

On 9/1/22 16:05, Jonathan S. Katz wrote:
> On 9/1/22 9:06 AM, Tomas Vondra wrote:
>>
>>
>> On 8/30/22 15:15, Jonathan S. Katz wrote:
>>> On 8/18/22 3:29 AM, Tomas Vondra wrote:
>>>>
>>>>
>>>> On 8/18/22 03:32, David Rowley wrote:
>>>
>>>>> Here are a couple of patches to demo the idea.
>>>>>
>>>>
>>>> Yeah, that's an option too. I should have mentioned it along with the
>>>> cpu_operator_cost.
>>>>
>>>> BTW would you mind taking a look at the costing? I think it's fine, but
>>>> it would be good if someone not involved in the patch takes a look.
>>>
>>> With RMT hat on, just a friendly reminder that this is still on the open
>>> items list[1] -- we have the Beta 4 release next week and it would be
>>> great if we can get this resolved prior to it.
>>>
>>
>> I know. I'll fix this by tweaking one of the cost gucs, mentioned by
>> David.
> 
> Great -- thanks for the update!
> 

I've pushed the fix to 15+master. In the end I just used David's patches
that set parallel_setup_cost to 0.


regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
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