Rework proxy_cache fix to restore performance

Adjustment to the fix made in I7fb134cac3604f8fe62e220fb24a0945d0a1c56f.

Fixes: #4747
Change-Id: I2f1010b0abc1faa892f5e346e58f9c4a3867622f

1 files changed, 12 insertions, 2 deletions

diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index aa7b7f688..22799dab5 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -793,6 +793,18 @@ class ColumnElement(
             s.update(c.proxy_set)
         return s
 
+    def _uncached_proxy_set(self):
+        """An 'uncached' version of proxy set.
+
+        This is so that we can read annotations from the list of columns
+        without breaking the caching of the above proxy_set.
+
+        """
+        s = util.column_set([self])
+        for c in self._proxies:
+            s.update(c._uncached_proxy_set())
+        return s
+
     def shares_lineage(self, othercolumn):
         """Return True if the given :class:`.ColumnElement`
         has a common ancestor to this :class:`.ColumnElement`."""
@@ -4386,8 +4398,6 @@ class AnnotatedColumnElement(Annotated):
     def __init__(self, element, values):
         Annotated.__init__(self, element, values)
         ColumnElement.comparator._reset(self)
-        if self._proxies:
-            ColumnElement.proxy_set._reset(self)
         for attr in ("name", "key", "table"):
             if self.__dict__.get(attr, False) is None:
                 self.__dict__.pop(attr)