Re: Fix generate_useful_gather_paths for parallel unsafe pathkeys

From: Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
To: James Coleman <jtc331(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, luis(dot)roberto(at)siscobra(dot)com(dot)br, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>
Subject: Re: Fix generate_useful_gather_paths for parallel unsafe pathkeys
Date: 2020-12-16 01:23:45
Message-ID: d8ddcad1-b7af-5ef8-e087-f6d6b204d0b7@enterprisedb.com
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Hi,

I reviewed the patch series, tweaked a couple comments, added commit
messages etc. Barring objections, I'll push this in a couple days.

One thing that annoys me is that it breaks ABI because it adds two new
parameters to find_em_expr_usable_for_sorting_rel, but I don't think we
can get around that. We could assume require_parallel_safe=true, but we
still need to pass the PlannerInfo pointer.

regards

--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Attachment Content-Type Size
0001-Consider-unsorted-paths-in-generate_useful_gather-v4.patch text/x-patch 3.3 KB
0002-Check-parallel-safety-in-generate_useful_gather_p-v4.patch text/x-patch 8.5 KB
0003-Disallow-SRFs-when-considering-sorts-below-Gather-v4.patch text/x-patch 4.5 KB
0004-Don-t-search-for-volatile-expr-in-find_em_expr_us-v4.patch text/x-patch 2.6 KB
0005-Improve-find_em_expr_usable_for_sorting_rel-comme-v4.patch text/x-patch 2.4 KB

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