[SQL Lab] Add function names to autocomplete (#9012)

superset/db_engine_specs/hive.py

@@ -19,7 +19,7 @@ import os
 import re
 import time
 from datetime import datetime
-from typing import Any, Dict, List, Optional, Tuple
+from typing import Any, Dict, List, Optional, Tuple, TYPE_CHECKING
 from urllib import parse
 
 from sqlalchemy import Column
@@ -34,6 +34,10 @@ from superset.db_engine_specs.base import BaseEngineSpec
 from superset.db_engine_specs.presto import PrestoEngineSpec
 from superset.utils import core as utils
 
+if TYPE_CHECKING:
+    # prevent circular imports
+    from superset.models.core import Database  # pylint: disable=unused-import
+
 QueryStatus = utils.QueryStatus
 config = app.config
 
@@ -422,3 +426,14 @@ class HiveEngineSpec(PrestoEngineSpec):
     ):  # pylint: disable=arguments-differ
         kwargs = {"async": async_}
         cursor.execute(query, **kwargs)
+
+    @classmethod
+    def get_function_names(cls, database: "Database") -> List[str]:
+        """
+        Get a list of function names that are able to be called on the database.
+        Used for SQL Lab autocomplete.
+
+        :param database: The database to get functions for
+        :return: A list of function names useable in the database
+        """
+        return database.get_df("SHOW FUNCTIONS")["tab_name"].tolist()