Fix: ensure Redshift's _fetch_native_df respects case-sensitivity

sqlmesh/core/engine_adapter/redshift.py

@@ -128,7 +128,16 @@ def _fetch_native_df(
     ) -> pd.DataFrame:
         """Fetches a Pandas DataFrame from the cursor"""
         self.execute(query, quote_identifiers=quote_identifiers)
-        return self.cursor.fetch_dataframe()
+
+        # We manually build the `DataFrame` here because the driver's `fetch_dataframe`
+        # method does not respect the active case-sensitivity configuration.
+        #
+        # Context: https://github.com/aws/amazon-redshift-python-driver/issues/238
+        fetcheddata = self.cursor.fetchall()
+        columns = [column[0] for column in self.cursor._getDescription() or []]
+
+        result = [tuple(column for column in rows) for rows in fetcheddata]
+        return pd.DataFrame(result, columns=columns)
 
     def _create_table_from_source_queries(
         self,

tests/core/engine_adapter/integration/test_integration_redshift.py

@@ -85,3 +85,12 @@ def test_columns(ctx: TestContext):
             {k: columns[k] for k in max_cols}
         ).values()
     ] == ["CHAR(max)", "CHAR(max)", "CHAR(max)", "VARCHAR(max)", "VARCHAR(max)", "VARCHAR(max)"]
+
+
+def test_fetch_native_df_respects_case_sensitivity(ctx: TestContext):
+    adapter = ctx.engine_adapter
+    adapter.execute("SET enable_case_sensitive_identifier TO true")
+    assert adapter.fetchdf('WITH t AS (SELECT 1 AS "C", 2 AS "c") SELECT * FROM t').to_dict == {
+        "C": {0: 1},
+        "c": {0: 2},
+    }