[GitHub] [doris] 924060929 commented on pull request #18869: [Feature](Nereids)support insert into select.

["924060929 (via GitHub)" <gi...@apache.org>]

924060929 commented on PR #18869:
URL: https://github.com/apache/doris/pull/18869#issuecomment-1516381077

   A known bug: insert into unique table without group by unique key will cause the replication different.
   
   3 replications maybe receive the data with different when exchange.
   
   e.g.
   ```
   +-----------+                        +--------------------------+ 
   | machine 1 |        exchange        |   machine 4 (replica 1)  |
   +-----------+                        +--------------------------+
   |   'a'     |                        |       'a', 'b', 'c'      |
   +-----------+                        +--------------------------+
                          \
   
   +-----------+                        +--------------------------+ 
   | machine 2 |                        |   machine 5 (replica 2)  |
   +-----------+          -             +--------------------------+
   |   'b'     |                        |       'c', 'a', 'b'      |
   +-----------+                        +--------------------------+
                          /
   
   +-----------+                        +--------------------------+ 
   | machine 3 |                        |   machine 5 (replica 2)  |
   +-----------+                        +--------------------------+ 
   |   'c'     |                        |       'b', 'c', 'a'      |
   +-----------+                        +--------------------------+
   
   ```
   
   so when insert into the table with unique key, we should let the final instance satisfy the distribution same with the key, and you should add a hash(unique key) require properties to the top of the select


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