fix: skip DESCRIBE TABLE EXTENDED AS JSON for foreign/federated tables

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 - Expose `job_id`, `job_run_id`, and `task_run_id` from the Databricks Jobs `dbt_task` runtime in `adapter_response`, enabling correlation between dbt runs and Databricks workflow executions via `run_results.json` ([#1451](https://github.com/databricks/dbt-databricks/pull/1451) closes [#722](https://github.com/databricks/dbt-databricks/issues/722))
 
+### Fixes
+
+- Skip `DESCRIBE TABLE EXTENDED ... AS JSON` for foreign/federated tables in `get_columns_in_relation`, avoiding repeated failures and extra latency on those sources ([#1472](https://github.com/databricks/dbt-databricks/pull/1472))
+
 ## dbt-databricks 1.12.0 (May 18, 2026)
 
 ### Features

dbt/adapters/databricks/impl.py

@@ -624,6 +624,7 @@ def get_columns_in_relation(  # type: ignore[override]
             # TODO: Replace with streaming table capability check when 17.1 is current version
             #       for SQL warehouses
             or relation.type == DatabricksRelationType.StreamingTable
+            or relation.is_foreign_table
         )
         return self.get_column_behavior.get_columns_in_relation(self, relation, use_legacy_logic)
 

tests/unit/test_adapter.py

@@ -1268,6 +1268,29 @@ def test_get_columns_materialized_view(self, mock_get_columns, adapter, unity_re
             assert result[0].dtype == "string"
             assert result[0].comment == "mv col"
 
+    @patch(
+        "dbt.adapters.databricks.behaviors.columns.GetColumnsByDescribe._get_columns_with_comments"
+    )
+    def test_get_columns_foreign_table_uses_legacy_logic(
+        self, mock_get_columns, adapter, unity_relation
+    ):
+        foreign_relation = DatabricksRelation.create(
+            database=unity_relation.database,
+            schema=unity_relation.schema,
+            identifier=unity_relation.identifier,
+            type=DatabricksRelationType.Foreign,
+        )
+        # Foreign/federated tables don't support AS JSON — always use legacy logic
+        with patch.object(adapter, "has_capability", return_value=True):
+            mock_get_columns.return_value = [
+                {"col_name": "federated_col", "data_type": "string", "comment": ""},
+            ]
+            result = adapter.get_columns_in_relation(foreign_relation)
+        mock_get_columns.assert_called_with(adapter, foreign_relation, "get_columns_comments")
+        assert len(result) == 1
+        assert result[0].column == "federated_col"
+        assert result[0].dtype == "string"
+
     @patch(
         "dbt.adapters.databricks.behaviors.columns.GetColumnsByDescribe._get_columns_with_comments"
     )