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Re: Row pattern recognition

Henson Choi <assam258@gmail.com>

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From: Henson Choi <assam258@gmail.com>
To: Tatsuo Ishii <ishii@postgresql.org>
Cc: david.g.johnston@gmail.com, vik@postgresfriends.org, jacob.champion@enterprisedb.com, er@xs4all.nl, peter@eisentraut.org, pgsql-hackers@postgresql.org
Date: 2026-01-04T15:47:58Z
Lists: pgsql-hackers

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Hi Ishii-san,

I've been working on an NFA implementation prototype.

This is a very early prototype - still buggy and incomplete,
but shows the basic approach. Attached HTML file - open in
browser (runs locally, no server needed).

I used JavaScript for quick prototyping and visualization.
The actual PostgreSQL implementation would be in C, but the
algorithm logic remains the same.

To test:
1. Use default pattern
2. Enter variables sequentially: A, B, C, D, E, F, G, H, I
3. Try different patterns and options in the UI

Implemented:
- Patterns: *, +, ?, (A|B), (A B)+
- Reluctant quantifiers: A+?, A*? (switches to reluctant mode)
  Note: This part probably has issues
- Execution trace with state visualization
- Context management: multiple matches, absorption
- Options: SKIP modes, output modes

Many rough edges, especially reluctant matching.
Just sharing the direction.

My responses may be slow due to company work during weekdays.

Best regards,
Henson

Commits

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

  1. Adjust cross-version upgrade tests for seg_out() fix

  2. Rationalize error comments in partition split/merge tests

  3. Add fast path for foreign key constraint checks

  4. Fix assorted pretty-trivial memory leaks in the backend.

  5. Add temporal FOREIGN KEY contraints

  6. Add trailing commas to enum definitions

  7. Remove obsolete executor cleanup code