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From: Henson Choi <[email protected]>
To: jian he <[email protected]>
To: Tatsuo Ishii <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Subject: Re: Row pattern recognition
Date: Fri, 26 Jun 2026 10:23:53 +0900
Message-ID: <CAAAe_zBAwUbzahW3wFM+toS6Ap565j1q9SOa0irhYSRTujGbyA@mail.gmail.com> (raw)
In-Reply-To: <CAAAe_zAjkjUZHMqu5DjgZH9ZZ6D5v4bBJy60ziwhHRoohnB7Zg@mail.gmail.com>
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Hi all,

A quick heads-up for this thread, cross-referenced from another one.

Haibo Yan has a patch series adding DISTINCT support to plain aggregate
window functions [1]. As it touches window-aggregate frame handling, I
applied it on top of the current RPR patch set and built the two together.
They combine cleanly today: no rebase conflict, and the regression tests
pass with no change to code or tests.

This is structural, not luck. RPR requires the frame to start at CURRENT
ROW, while that feature requires UNBOUNDED PRECEDING, so a single window can
satisfy at most one of them -- no overlap.

That said, the DISTINCT roadmap plans to relax its UNBOUNDED-PRECEDING
restriction (the sliding-frame patches), while RPR's CURRENT-ROW requirement
is fixed by the standard. So as those frame restrictions are lifted the two
could start to overlap, and at that point we'd likely need to review the
related frame-handling changes together. Nothing to act on now -- just
flagging it so we keep an eye on it.

Full review of the DISTINCT series is in the other thread [1].

[1]
https://www.postgresql.org/message-id/[email protected]...

Best,
Henson


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