BUG: MultiIndex not raising AttributeError with a million records (#18165)

Author: WillAyd

doc/source/whatsnew/v0.22.0.txt

@@ -100,7 +100,7 @@ Indexing
 
 - Bug in :func:`Series.truncate` which raises ``TypeError`` with a monotonic ``PeriodIndex`` (:issue:`17717`)
 - Bug in :func:`DataFrame.groupby` where key as tuple in a ``MultiIndex`` were interpreted as a list of keys (:issue:`17979`)
--
+- Bug where a ``MultiIndex`` with more than a million records was not raising ``AttributeError`` as expected (:issue:`18165`)
 -
 
 I/O

pandas/core/indexes/multi.py

@@ -446,6 +446,17 @@ def _shallow_copy_with_infer(self, values=None, **kwargs):
                               **kwargs)
         return self._shallow_copy(values, **kwargs)
 
+    @Appender(_index_shared_docs['__contains__'] % _index_doc_kwargs)
+    def __contains__(self, key):
+        hash(key)
+        try:
+            self.get_loc(key)
+            return True
+        except (LookupError, TypeError):
+            return False
+
+    contains = __contains__
+
     @Appender(_index_shared_docs['_shallow_copy'])
     def _shallow_copy(self, values=None, **kwargs):
         if values is not None:
@@ -1370,17 +1381,6 @@ def nlevels(self):
     def levshape(self):
         return tuple(len(x) for x in self.levels)
 
-    @Appender(_index_shared_docs['__contains__'] % _index_doc_kwargs)
-    def __contains__(self, key):
-        hash(key)
-        try:
-            self.get_loc(key)
-            return True
-        except LookupError:
-            return False
-
-    contains = __contains__
-
     def __reduce__(self):
         """Necessary for making this object picklable"""
         d = dict(levels=[lev for lev in self.levels],

pandas/tests/indexes/test_multi.py

@@ -2981,3 +2981,13 @@ def test_nan_stays_float(self):
         assert pd.isna(df0.index.get_level_values(1)).all()
         # the following failed in 0.14.1
         assert pd.isna(dfm.index.get_level_values(1)[:-1]).all()
+
+    def test_million_record_attribute_error(self):
+        # GH 18165
+        r = list(range(1000000))
+        df = pd.DataFrame({'a': r, 'b': r},
+                          index=pd.MultiIndex.from_tuples([(x, x) for x in r]))
+
+        with pytest.raises(AttributeError,
+                           message="'Series' object has no attribute 'foo'"):
+            df['a'].foo()