Re: Support "Right Semi Join" plan shapes

From: Richard Guo <guofenglinux(at)gmail(dot)com>
To: Alena Rybakina <lena(dot)ribackina(at)yandex(dot)ru>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, wenhui qiu <qiuwenhuifx(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>
Subject: Re: Support "Right Semi Join" plan shapes
Date: 2024-03-05 02:44:11
Message-ID: CAMbWs4_EodKyroqCW1fT=yuCPK9xvRgHkFCvHETPwNeZfg4pWw@mail.gmail.com
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On Tue, Jan 30, 2024 at 2:51 PM Alena Rybakina <lena(dot)ribackina(at)yandex(dot)ru>
wrote:

> I have reviewed your patch and I think it is better to add an Assert for
> JOIN_RIGHT_SEMI to the ExecMergeJoin and ExecNestLoop functions to
> prevent the use of RIGHT_SEMI for these types of connections (NestedLoop
> and MergeJoin).

Hmm, I don't see why this is necessary. The planner should already
guarantee that we won't have nestloops/mergejoins with right-semi joins.

Thanks
Richard

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