diff --git a/superset/connectors/sqla/models.py b/superset/connectors/sqla/models.py
index e6549260d00e7..06261fc5c6415 100644
--- a/superset/connectors/sqla/models.py
+++ b/superset/connectors/sqla/models.py
@@ -47,8 +47,10 @@ def query(self, query_obj):
         error_message = None
         qry = db.session.query(Annotation)
         qry = qry.filter(Annotation.layer_id == query_obj['filter'][0]['val'])
-        qry = qry.filter(Annotation.start_dttm >= query_obj['from_dttm'])
-        qry = qry.filter(Annotation.end_dttm <= query_obj['to_dttm'])
+        if query_obj['from_dttm']:
+            qry = qry.filter(Annotation.start_dttm >= query_obj['from_dttm'])
+        if query_obj['to_dttm']:
+            qry = qry.filter(Annotation.end_dttm <= query_obj['to_dttm'])
         status = QueryStatus.SUCCESS
         try:
             df = pd.read_sql_query(qry.statement, db.engine)
diff --git a/superset/viz.py b/superset/viz.py
index 30e8e80da1cda..59dd70b179bd0 100644
--- a/superset/viz.py
+++ b/superset/viz.py
@@ -382,7 +382,8 @@ def get_df_payload(self, query_obj=None):
         if query_obj and not is_loaded:
             try:
                 df = self.get_df(query_obj)
-                if hasattr(self.datasource.database, 'db_engine_spec'):
+                if hasattr(self.datasource, 'database') and \
+                        hasattr(self.datasource.database, 'db_engine_spec'):
                     db_engine_spec = self.datasource.database.db_engine_spec
                     df = db_engine_spec.adjust_df_column_names(df, self.form_data)
                 if self.status != utils.QueryStatus.FAILED: