| From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Teaching planner to short-circuit empty UNION/EXCEPT/INTERSECT inputs |
| Date: | 2025-10-02 12:09:27 |
| Message-ID: | CAApHDvpk88w3MrzgZShROjQw3NPK54YKr_hOi0++0QKGwTq+-g@mail.gmail.com |
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On Thu, 2 Oct 2025 at 16:21, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I'm wondering if it could be shortened a great deal by
> handling left-input-dummy and EXCEPT-ALL-with-right-input-dummy
> but leaving the EXCEPT-with-right-input-dummy case unimproved.
Good idea. Less code and still get to keep the one that did well in
the benchmark. See attached.
I ended up splitting the patch in two. 0001 for UNION only, then 0002
for the INTERSECT and EXCEPT.
David
| Attachment | Content-Type | Size |
|---|---|---|
| v2-0001-Teach-UNION-planner-to-remove-dummy-inputs.patch | application/octet-stream | 6.9 KB |
| v2-0002-Teach-planner-to-short-circuit-EXCEPT-INTERSECT-w.patch | application/octet-stream | 7.3 KB |
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