Re: Fix CPU cost of right-semi and right-anti hash joins

From: Richard Guo <guofenglinux(at)gmail(dot)com>
To: wenhui qiu <qiuwenhuifx(at)gmail(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Fix CPU cost of right-semi and right-anti hash joins
Date: 2026-08-18 00:21:58
Message-ID: CAMbWs48TX07h--OaZix=0DML9u7N0zcUHSVfG-0jKqvmLTbTCg@mail.gmail.com
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On Mon, Aug 17, 2026 at 12:58 PM wenhui qiu <qiuwenhuifx(at)gmail(dot)com> wrote:
>> The cpu_tuple_cost change looks right: RIGHT_SEMI/RIGHT_ANTI emit
>> inner-side rows, while hashjointuples is based on the tuples processed
>> by the hash join and can be much larger. The path LGTM

Thanks for the review.

Regarding back-patching, this fix can change plans, and plan changes
in a minor release are a problem for users. But maybe we can still
push it to v19?

- Richard

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