[incubator-superset] branch master updated: [sql_lab] Improve performance, only use slow func when needed (#9612)

[dpgaspar]

This is an automated email from the ASF dual-hosted git repository.

dpgaspar pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-superset.git


The following commit(s) were added to refs/heads/master by this push:
     new 76764ac  [sql_lab] Improve performance, only use slow func when needed 
(#9612)
76764ac is described below

commit 76764acfc16ef16583dcad30472d93346deaa796
Author: Daniel Vaz Gaspar <danielvazgas...@gmail.com>
AuthorDate: Thu Apr 23 09:35:57 2020 +0100

    [sql_lab] Improve performance, only use slow func when needed (#9612)
---
 superset/sql_parse.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/superset/sql_parse.py b/superset/sql_parse.py
index 35c6e9f..b39fc44 100644
--- a/superset/sql_parse.py
+++ b/superset/sql_parse.py
@@ -60,12 +60,14 @@ class ParsedQuery:
         logger.debug("Parsing with sqlparse statement: %s", self.sql)
         self._parsed = sqlparse.parse(self.stripped())
         for statement in self._parsed:
-            self.__extract_from_token(statement)
             self._limit = _extract_limit_from_query(statement)
-        self._table_names = self._table_names - self._alias_names
 
     @property
     def tables(self) -> Set[str]:
+        if not self._table_names:
+            for statement in self._parsed:
+                self.__extract_from_token(statement)
+            self._table_names = self._table_names - self._alias_names
         return self._table_names
 
     @property