Fix spurious warnings and bogus index when reflecting Iceberg tables

Author: metadaddy

trino/sqlalchemy/dialect.py

@@ -218,7 +218,7 @@ def _get_partitions(
         connection: Connection,
         table_name: str,
         schema: str = None
-    ) -> List[Dict[str, List[Any]]]:
+    ) -> List[str] | None:
         schema = schema or self._get_default_schema_name(connection)
         query = dedent(
             f"""
@@ -227,6 +227,17 @@ def _get_partitions(
         ).strip()
         res = connection.execute(sql.text(query))
         partition_names = [desc[0] for desc in res.cursor.description]
+        data_types = [desc[1] for desc in res.cursor.description]
+        # Compare the column names and types to the shape of an Iceberg $partitions table
+        if (partition_names == ['partition', 'record_count', 'file_count', 'total_size', 'data']
+                and data_types[0].startswith('row(')
+                and data_types[1] == 'bigint'
+                and data_types[2] == 'bigint'
+                and data_types[3] == 'bigint'
+                and data_types[4].startswith('row(')):
+            # This is an Iceberg $partitions table - these match the partition metadata columns
+            return None
+        # This is a Hive table - these are the partition names
         return partition_names
 
     def get_pk_constraint(self, connection: Connection, table_name: str, schema: str = None, **kw) -> Dict[str, Any]:
@@ -326,7 +337,7 @@ def get_indexes(self, connection: Connection, table_name: str, schema: str = Non
         try:
             partitioned_columns = self._get_partitions(connection, f"{table_name}", schema)
         except Exception as e:
-            # e.g. it's not a Hive table or an unpartitioned Hive table
+            # e.g. it's an unpartitioned Hive table
             logger.debug("Couldn't fetch partition columns. schema: %s, table: %s, error: %s", schema, table_name, e)
         if not partitioned_columns:
             return []