From 38f67a44ca9e4dfa9d03776bcafc247e48783ec9 Mon Sep 17 00:00:00 2001
From: Ville Brofeldt <33317356+villebro@users.noreply.github.com>
Date: Wed, 25 Nov 2020 12:55:00 +0200
Subject: [PATCH] fix: mutating input df in viz.py (#11795)

---
 superset/viz.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/superset/viz.py b/superset/viz.py
index 0a8a7028ed..ab08fe4e70 100644
--- a/superset/viz.py
+++ b/superset/viz.py
@@ -1671,6 +1671,7 @@ class DistributionBarViz(BaseViz):
         # pandas will throw away nulls when grouping/pivoting,
         # so we substitute NULL_STRING for any nulls in the necessary columns
         filled_cols = self.groupby + columns
+        df = df.copy()
         df[filled_cols] = df[filled_cols].fillna(value=NULL_STRING)
 
         row = df.groupby(self.groupby).sum()[metrics[0]].copy()