| From: | Tatsuo Ishii <ishii(at)postgresql(dot)org> |
|---|---|
| To: | assam258(at)gmail(dot)com |
| Cc: | vik(at)postgresfriends(dot)org, er(at)xs4all(dot)nl, jacob(dot)champion(at)enterprisedb(dot)com, david(dot)g(dot)johnston(at)gmail(dot)com, peter(at)eisentraut(dot)org, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Row pattern recognition |
| Date: | 2026-02-17 06:39:22 |
| Message-ID: | 20260217.153922.1932150435522001258.ishii@postgresql.org |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
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| Lists: | pgsql-hackers |
Hi Henson,
> Anchored pattern absorption optimization
>
> PREFIX elements (e.g., START in "START A+ B") block absorption,
> causing O(n^2) regression for anchored patterns. A draft design
> exists: track an alternate "shadow" path that skips PREFIX and
> starts at the BODY region, enabling absorption eligibility checks
> while the original path processes PREFIX normally. This keeps
> concurrent contexts bounded to PREFIX_length + 1, maintaining
> O(n) complexity. The design needs further refinement before
> implementation.
What do you mean by "Anchored pattern" here? I am asking because R010
(RPR in Window clause) does not allow to use anchors (^ and $) in
PATTERN clause.
Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp
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