[SPARK-47528] Add UserDefinedType support to DataTypeUtils.canWrite

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.0.0
• Fix Version/s: 4.0.0
• Component/s: SQL
• Labels: pull-request-available
• Assignee: L. C. Hsieh
• Reporter: L. C. Hsieh
• Created: 23/Mar/24 22:43
• Updated: 24/Mar/24 17:27
• Resolved: 24/Mar/24 08:28

Description

Our customer hits an issue recently when they tries to save a DataFrame containing some UDTs as table (`saveAsTable`). The error looks like:

```

• Cannot write 'xxx': struct<...> is incompatible with struct<...>
  ```

The catalog strings between two sides are actually same which makes the customer confused.

It is because `DataTypeUtils.canWrite` doesn't handle `UserDefinedType`. If the `UserDefinedType`'s underlying sql type is same as read side, `canWrite` should return true for two sides.

Issue Links

• links to: GitHub Pull Request #45678