FileStorages previously saved indexes after a certain

number of writes.  This was done during the last phase of two-phase
commit, which made this critical phase more subject to errors than
it should have been.  Also, for large databases, saves were done so
infrequently as to be useless.  The feature was removed to reduce
the chance for errors during the last phase of two-phase commit.

src/CHANGES.txt

@@ -114,6 +114,18 @@ Bugs Fixed
 
 Bugs Fixed:
 
+- FileStorages previously saved indexes after a certain
+  number of writes.  This was done during the last phase of two-phase
+  commit, which made this critical phase more subject to errors than
+  it should have been.  Also, for large databases, saves were done so
+  infrequently as to be useless.  The feature was removed to reduce
+  the chance for errors during the last phase of two-phase commit.
+
+- File storages previously kept an internal object id to
+  transaction id mapping as an optimization. This mapping caused
+  excessive memory usage and failures during the last phase of
+  two-phase commit. This optimization has been removed.
+
 - Refactored handling of invalidations on ZEO clients to fix
   a possible ordering problem for invalidation messages.
 

src/ZODB/FileStorage/FileStorage.py

@@ -95,8 +95,6 @@ class FileStorage(BaseStorage.BaseStorage,
     # Set True while a pack is in progress; undo is blocked for the duration.
     _pack_is_in_progress = False
 
-    _records_before_save = 10000
-
     def __init__(self, file_name, create=False, read_only=False, stop=None,
                  quota=None):
 
@@ -171,8 +169,6 @@ class FileStorage(BaseStorage.BaseStorage,
                 )
             self._save_index()
 
-        self._records_before_save = max(self._records_before_save,
-                                        len(self._index))
         self._ltid = tid
 
         # self._pos should always point just past the last
@@ -660,9 +656,6 @@ class FileStorage(BaseStorage.BaseStorage,
         finally:
             self._lock_release()
 
-    # Keep track of the number of records that we've written
-    _records_written = 0
-
     def _finish(self, tid, u, d, e):
         nextpos=self._nextpos
         if nextpos:
@@ -679,15 +672,6 @@ class FileStorage(BaseStorage.BaseStorage,
 
             self._index.update(self._tindex)
 
-            # Update the number of records that we've written
-            # +1 for the transaction record
-            self._records_written += len(self._tindex) + 1
-            if self._records_written >= self._records_before_save:
-                self._save_index()
-                self._records_written = 0
-                self._records_before_save = max(self._records_before_save,
-                                                len(self._index))
-
         self._ltid = tid
 
     def _abort(self):

src/ZODB/tests/testFileStorage.py

@@ -179,26 +179,6 @@ class FileStorageTests(
         self.open()
         self.assertEqual(self._storage._saved, 1)
 
-    # This would make the unit tests too slow
-    # check_save_after_load_that_worked_hard(self)
-
-    def check_periodic_save_index(self):
-
-        # Check the basic algorithm
-        oldsaved = self._storage._saved
-        self._storage._records_before_save = 10
-        for i in range(4):
-            self._dostore()
-        self.assertEqual(self._storage._saved, oldsaved)
-        self._dostore()
-        self.assertEqual(self._storage._saved, oldsaved+1)
-
-        # Now make sure the parameter changes as we get bigger
-        for i in range(20):
-            self._dostore()
-
-        self.failUnless(self._storage._records_before_save > 20)
-
     def checkStoreBumpsOid(self):
         # If .store() is handed an oid bigger than the storage knows
         # about already, it's crucial that the storage bump its notion