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Re: apply_scanjoin_target_to_paths and partitionwise join

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: arne.roland@malkut.net
Cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Zhihong Yu <zyu@yugabyte.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Tom Lane <tgl@sss.pgh.pa.us>, Julien Rouhaud <rjuju123@gmail.com>, Etsuro Fujita <etsuro.fujita@gmail.com>
Date: 2024-05-24T18:47:00Z
Lists: pgsql-hackers 
On Fri, May 24, 2024 at 2:02 PM <arne.roland@malkut.net> wrote:
> I am not sure, whether it's really a bug. I personally wouldn't be brave
> enough to back patch this. I don't want to deal with complaining end
> users. Suddenly their optimizer, which always had horrible estimates,
> was actually able to do harmful stuff with them. Only due to a minor
> version upgrade. I think that's a bad idea to backpatch something with
> complex performance implications. Especially since they might even be
> based on potentially inaccurate data...

+1.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

Commits

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

  1. Remove redundant SET enable_partitionwise_join = on.

  2. Don't reset the pathlist of partitioned joinrels.

  3. Allow left join removals and unique joins on partitioned tables

  4. Consider fractional paths in generate_orderedappend_paths

  5. Fix handling of targetlist SRFs when scan/join relation is known empty.