| From: | Richard Guo <guofenglinux(at)gmail(dot)com> |
|---|---|
| To: | Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Redundant restriction checks in apply_child_basequals |
| Date: | 2026-02-19 07:36:00 |
| Message-ID: | CAMbWs4-vLmGXaUEZyOMacN0BVfqWCt2tM-eDVWdDfJnOQaauGg@mail.gmail.com |
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| Lists: | pgsql-hackers |
While working on bug #19412 [1], I noticed $subject. For each child
qual translated from a parent rel's qual, apply_child_basequals calls
eval_const_expressions to simplify it, and then calls
restriction_is_always_false and restriction_is_always_true immediately
afterward to reduce NullTest expressions. Since the planner performs
NullTest deduction during constant folding, I think the call to
restriction_is_always_false and restriction_is_always_true is now
redundant and wastes CPU cycles.
Attached is a patch to remove them.
[1] https://postgr.es/m/19412-1d0318089b86859e@postgresql.org
- Richard
| Attachment | Content-Type | Size |
|---|---|---|
| v1-0001-Remove-redundant-restriction-checks-in-apply_chil.patch | application/octet-stream | 4.4 KB |
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