force limit only when there is no existing limit

superset/sql_lab.py

@@ -171,6 +171,7 @@ def handle_error(msg):
     # Limit enforced only for retrieving the data, not for the CTA queries.
     superset_query = SupersetQuery(rendered_query)
     executed_sql = superset_query.stripped()
+    SQL_MAX_ROWS = int(app.config.get('SQL_MAX_ROW', None))
     if not superset_query.is_select() and not database.allow_dml:
         return handle_error(
             'Only `SELECT` statements are allowed against this database')
@@ -185,7 +186,8 @@ def handle_error(msg):
                 query.user_id, start_dttm.strftime('%Y_%m_%d_%H_%M_%S'))
         executed_sql = superset_query.as_create_table(query.tmp_table_name)
         query.select_as_cta_used = True
-    elif (query.limit and superset_query.is_select()):
+    elif (not query.limit and superset_query.is_select() and SQL_MAX_ROWS):
+        query.limit = SQL_MAX_ROWS
         executed_sql = database.apply_limit_to_sql(executed_sql, query.limit)
         query.limit_used = True
 

superset/utils.py

@@ -882,3 +882,17 @@ def split_adhoc_filters_into_base_filters(fd):
         fd['having_filters'] = simple_having_filters
         fd['filters'] = simple_where_filters
         del fd['adhoc_filters']
+
+
+def get_limit_from_sql(sql):
+    sql = sql.lower()
+    limit = None
+    tokens = sql.split()
+    try:
+        if 'limit' in tokens:
+            limit_pos = tokens.index('limit') + 1
+            limit = int(tokens[limit_pos])
+    except Exception as e:
+        # fail quietly so we can get the more intelligible error from the database.
+        logging.error('Non-numeric limit added.\n{}'.format(e))
+    return limit

superset/views/core.py

@@ -2394,7 +2394,7 @@ def sql_json(self):
 
         query = Query(
             database_id=int(database_id),
-            limit=int(app.config.get('SQL_MAX_ROW', None)),
+            limit=utils.get_limit_from_sql(sql),
             sql=sql,
             schema=schema,
             select_as_cta=request.form.get('select_as_cta') == 'true',

tests/celery_tests.py

@@ -196,13 +196,11 @@ def test_run_async_query(self):
         self.assertEqual([{'name': 'Admin'}], df.to_dict(orient='records'))
         self.assertEqual(QueryStatus.SUCCESS, query.status)
         self.assertTrue('FROM tmp_async_1' in query.select_sql)
-        self.assertTrue('LIMIT 666' in query.select_sql)
         self.assertEqual(
             'CREATE TABLE tmp_async_1 AS \nSELECT name FROM ab_role '
             "WHERE name='Admin'", query.executed_sql)
         self.assertEqual(sql_where, query.sql)
         self.assertEqual(0, query.rows)
-        self.assertEqual(666, query.limit)
         self.assertEqual(False, query.limit_used)
         self.assertEqual(True, query.select_as_cta)
         self.assertEqual(True, query.select_as_cta_used)