diff --git a/superset/connectors/sqla/models.py b/superset/connectors/sqla/models.py
index a080507075..8b731ecb19 100644
--- a/superset/connectors/sqla/models.py
+++ b/superset/connectors/sqla/models.py
@@ -1391,7 +1391,7 @@ class SqlaTable(Model, BaseDatasource):  # pylint: disable=too-many-public-metho
                     if c not in metrics and c in groupby_series_columns
                 ]
                 top_groups = self._get_top_groups(
-                    result.df, dimensions, groupby_series_columns
+                    result.df, dimensions, groupby_series_columns, columns_by_name
                 )
                 qry = qry.where(top_groups)
 
@@ -1436,20 +1436,23 @@ class SqlaTable(Model, BaseDatasource):  # pylint: disable=too-many-public-metho
         return ob
 
     def _get_top_groups(
-        self, df: pd.DataFrame, dimensions: List[str], groupby_exprs: Dict[str, Any],
+        self,
+        df: pd.DataFrame,
+        dimensions: List[str],
+        groupby_exprs: Dict[str, Any],
+        columns_by_name: Dict[str, TableColumn],
     ) -> ColumnElement:
-        column_map = {column.column_name: column for column in self.columns}
         groups = []
         for _unused, row in df.iterrows():
             group = []
             for dimension in dimensions:
-                value = row[dimension]
+                value = utils.normalize_prequery_result_type(row[dimension])
 
                 # Some databases like Druid will return timestamps as strings, but
                 # do not perform automatic casting when comparing these strings to
                 # a timestamp. For cases like this we convert the value from a
                 # string into a timestamp.
-                if column_map[dimension].is_temporal and isinstance(value, str):
+                if columns_by_name[dimension].is_temporal and isinstance(value, str):
                     dttm = dateutil.parser.parse(value)
                     value = text(self.db_engine_spec.convert_dttm("TIMESTAMP", dttm))
 
diff --git a/superset/utils/core.py b/superset/utils/core.py
index 9f30c64d91..b99036f5d7 100644
--- a/superset/utils/core.py
+++ b/superset/utils/core.py
@@ -1813,3 +1813,35 @@ def escape_sqla_query_binds(sql: str) -> str:
             sql = sql.replace(bind, bind.replace(":", "\\:"))
             processed_binds.add(bind)
     return sql
+
+
+def normalize_prequery_result_type(
+    value: Union[str, int, float, bool, np.generic]
+) -> Union[str, int, float, bool]:
+    """
+    Convert a value that is potentially a numpy type into its equivalent Python type.
+
+    :param value: primitive datatype in either numpy or python format
+    :return: equivalent primitive python type
+    >>> normalize_prequery_result_type('abc')
+    'abc'
+    >>> normalize_prequery_result_type(True)
+    True
+    >>> normalize_prequery_result_type(123)
+    123
+    >>> normalize_prequery_result_type(np.int16(123))
+    123
+    >>> normalize_prequery_result_type(np.uint32(123))
+    123
+    >>> normalize_prequery_result_type(np.int64(123))
+    123
+    >>> normalize_prequery_result_type(123.456)
+    123.456
+    >>> normalize_prequery_result_type(np.float32(123.456))
+    123.45600128173828
+    >>> normalize_prequery_result_type(np.float64(123.456))
+    123.456
+    """
+    if isinstance(value, np.generic):
+        return value.item()
+    return value