[GitHub] mistercrunch commented on a change in pull request #4947: [sql lab] a better approach at limiting queries

[GitBox <gi...@apache.org>]

mistercrunch commented on a change in pull request #4947: [sql lab] a better approach at limiting queries
URL: https://github.com/apache/incubator-superset/pull/4947#discussion_r187496738
 
 

 ##########
 File path: superset/db_engine_specs.py
 ##########
 @@ -88,6 +90,23 @@ def extra_table_metadata(cls, database, table_name, schema_name):
         """Returns engine-specific table metadata"""
         return {}
 
+    @classmethod
+    def apply_limit_to_sql(cls, sql, limit, database):
+        """Alters the SQL statement to apply a LIMIT clause"""
+        if cls.limit_method == LimitMethod.WRAP_SQL:
+            qry = (
+                select('*')
+                .select_from(
+                    TextAsFrom(text(sql), ['*']).alias('inner_qry'),
+                )
+                .limit(limit)
+            )
+            return database.compile_sqla_query(qry)
+        elif LimitMethod.FORCE_LIMIT:
+            no_limit = re.sub(r'(?i)\s+LIMIT\s+\d+;?(\s|;)*$', '', sql)
 
 Review comment:
   I barely understand what I wrote here :/

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