Streamline what column changes are considered breaking #6043
Description
There are several types of column changes we can make, so we need to understand clearly what changes are considered 100% breaking:
| Change type | Breaking? | Reason |
|---|---|---|
| Adding a column | false |
Doesn't break any data consistency |
| Adding a column to a PK | false |
Doesn't break any data consistency |
| Removing a column from a PK | true |
May introduce PK conflicts in the data and lead to data loss |
| Removing a column | true |
Data loss |
| Changing composite PK columns order | false |
May change the partitioning, but otherwise, harmless |
| Changing column type | true |
Unknown if we can migrate |