gavinchou opened a new pull request, #66849:
URL: https://github.com/apache/doris/pull/66849

   ### What problem does this PR solve?
   
   Issue Number: None
   
   Related PR: None
   
   Problem Summary:
   
   MIN_DELTA row-binlog scans previously classified each primary-key window 
only from its first and last operation. As a result, an update emitted 
`UPDATE_BEFORE` and `UPDATE_AFTER` rows even when the complete row image was 
unchanged, including multi-update chains that eventually returned to their 
original values.
   
   This change reads all AFTER/BEFORE value columns needed by MIN_DELTA, 
compares the first BEFORE image with the final AFTER image, and converts a 
net-zero update into `SKIP`. Comparison-only columns remain hidden from the SQL 
projection. Missing, incompatible, or unsupported BEFORE images preserve the 
existing UPDATE output conservatively.
   
   The tests cover direct no-op updates, changes in unprojected columns, 
multiple keys and columns, pending output across batch boundaries, and complex 
insert/delete/update chains that either return to the original image or finish 
changed.
   
   ### Release note
   
   MIN_DELTA row-binlog queries no longer return update rows when the complete 
row image is unchanged across the query window.
   
   ### Check List (For Author)
   
   - Test
       - [ ] Regression test
       - [x] Unit Test
           - `BlockReaderChangeNextBlockTest.*`: 18/18 passed under ASAN.
           - Release BE and Cloud targets compiled successfully.
       - [ ] Manual test
       - [ ] No need to test or manual test.
   
   - Behavior changed:
       - [ ] No.
       - [x] Yes. Net-zero updates are omitted from MIN_DELTA results.
   
   - Does this need documentation?
       - [ ] No.
       - [x] Yes. A follow-up documentation update is planned.
   
   ### Check List (For Reviewer who merge this PR)
   
   - [ ] Confirm the release note
   - [ ] Confirm test cases
   - [ ] Confirm document
   - [ ] Add branch pick label


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