Horton

Re: Row pattern recognition

Tatsuo Ishii <ishii@sraoss.co.jp>

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From: Tatsuo Ishii <ishii@sraoss.co.jp>
To: vik@postgresfriends.org, champion.p@gmail.com
Cc: pgsql-hackers@postgresql.org, er@xs4all.nl, peter@eisentraut.org
Date: 2024-04-24T03:12:44Z
Lists: pgsql-hackers

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Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add temporal FOREIGN KEY contraints

  2. Remove obsolete executor cleanup code

Hi Vik and Champion,

I think the current RPR patch is not quite correct in handling
count(*).

(using slightly modified version of Vik's example query)

SELECT v.a, count(*) OVER w
FROM (VALUES ('A'),('B'),('B'),('C')) AS v (a)
WINDOW w AS (
  ORDER BY v.a
  ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
  PATTERN (B+)
  DEFINE B AS a = 'B'
)
 a | count 
---+-------
 A |     0
 B |     2
 B |      
 C |     0
(4 rows)

Here row 3 is skipped because the pattern B matches row 2 and 3. In
this case I think cont(*) should return 0 rathern than NULL for row 3.

What do you think?

Best reagards,
--
Tatsuo Ishii
SRA OSS LLC
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp