Horton

Re: Row pattern recognition

Vik Fearing <vik@postgresfriends.org>

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From: Vik Fearing <vik@postgresfriends.org>
To: Jacob Champion <jchampion@timescale.com>, Tatsuo Ishii <ishii@sraoss.co.jp>
Cc: er@xs4all.nl, pgsql-hackers@postgresql.org
Date: 2023-09-08T21:43:10Z
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

On 9/8/23 21:27, Jacob Champion wrote:
> On 9/7/23 20:54, Tatsuo Ishii wrote:

>>> But it's easy
>>> to come up with a pattern where that's the wrong order, like
>>>
>>>      PATTERN ( A+ (B|A)+ )
>>>
>>> Now "aaa" will be considered before "aab", which isn't correct.
>>
>> Can you explain a little bit more? I think 'aaa' matches a regular
>> expression 'a+(b|a)+' and should be no problem before "aab" is
>> considered.
> 
> Assuming I've understood the rules correctly, we're not allowed to
> classify the last row as 'A' if it also matches 'B'. Lexicographic
> ordering takes precedence, so we have to try "aab" first. Otherwise our
> query could return different results compared to another implementation.


Your understanding is correct.
-- 
Vik Fearing