Horton

Re: Row pattern recognition

Chao Li <li.evan.chao@gmail.com>

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From: Chao Li <li.evan.chao@gmail.com>
To: Vik Fearing <vik@postgresfriends.org>, Tatsuo Ishii <ishii@postgresql.org>
Cc: david.g.johnston@gmail.com, jacob.champion@enterprisedb.com, er@xs4all.nl, peter@eisentraut.org, pgsql-hackers@postgresql.org
Date: 2025-11-20T07:33:48Z
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 Nov 19, 2025, at 12:14, Chao Li <li.evan.chao@gmail.com> wrote:
> 
> 
> 9 - 0002 - parse_clause.c

I am continuing to review 0003

10 - 0003
```
+	Assert(list_length(patternVariables) == list_length(defineClause));
```

Is this assert true? From what I learned, pattern length doesn’t have to equal to define length. For example, I got an example from [1]:

```
Example 4
-- This example has three different patterns.
-- Comment two of them, to get error-free query.
SELECT company, price_date, price
  FROM stock_price
    MATCH_RECOGNIZE (
       partition by company
       order by price_date
       all rows per match
       pattern ( limit_50  up   up* down  down*  )
       define
           limit_50 as price <= 50.00,
           up   as price > prev(price),
           down as price < prev(price)
    )
   WHERE company = 'B'
   ORDER BY price_date;
```

In this example, pattern has 5 elements and define has only 3 elements.

11 - 0004 - plannodes.h
```
+	/* Row Pattern Recognition AFTER MACH SKIP clause */
+	RPSkipTo	rpSkipTo;		/* Row Pattern Skip To type */
```

Typo: MACH -> MATCH

I’d stop here, and continue 0005 tomorrow.


[1] https://link.springer.com/article/10.1007/s13222-022-00404-3

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/