Is your feature request related to a problem? Please describe.
When Auron Iceberg native scan falls back because the read schema contains unsupported data types, the fallback does not provide a specific never-convert reason.
For example, an Iceberg table with an unsupported decimal field falls back to Spark execution, but the plan does not clearly explain which field/type caused native scan conversion to be skipped.
Describe the solution you'd like
Add an Iceberg fallback reason for unsupported scan schema data types.
The reason should include the unsupported field names and their Spark SQL types, so users and developers can quickly identify why the Iceberg native scan was not selected.
Describe alternatives you've considered
One alternative is to keep silent fallback behavior and rely on plan inspection or debug logs.
That makes diagnosis harder, especially when the scan schema has many columns or nested types.
Additional context
This change should only improve fallback diagnostics. It should not change native Iceberg scan eligibility or execution behavior.
Is your feature request related to a problem? Please describe.
When Auron Iceberg native scan falls back because the read schema contains unsupported data types, the fallback does not provide a specific never-convert reason.
For example, an Iceberg table with an unsupported decimal field falls back to Spark execution, but the plan does not clearly explain which field/type caused native scan conversion to be skipped.
Describe the solution you'd like
Add an Iceberg fallback reason for unsupported scan schema data types.
The reason should include the unsupported field names and their Spark SQL types, so users and developers can quickly identify why the Iceberg native scan was not selected.
Describe alternatives you've considered
One alternative is to keep silent fallback behavior and rely on plan inspection or debug logs.
That makes diagnosis harder, especially when the scan schema has many columns or nested types.
Additional context
This change should only improve fallback diagnostics. It should not change native Iceberg scan eligibility or execution behavior.