Horton

Re: Row pattern recognition

Tatsuo Ishii <ishii@sraoss.co.jp>

View thread
From: Tatsuo Ishii <ishii@sraoss.co.jp>
To: jacob.champion@enterprisedb.com
Cc: vik@postgresfriends.org, pgsql-hackers@postgresql.org, er@xs4all.nl, peter@eisentraut.org
Date: 2024-04-26T06:09:32Z
Lists: pgsql-hackers

Commits

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

Attachments

> On Tue, Apr 23, 2024 at 8:13 PM Tatsuo Ishii <ishii@sraoss.co.jp> wrote:
>> 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.
> 
> I think returning zero would match Vik's explanation upthread [1],
> yes. Unfortunately I don't have a spec handy to double-check for
> myself right now.

Ok. I believe you and Vik are correct.
I am modifying the patch in this direction.
Attached is the regression diff after modifying the patch.

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