.

wcfs/internal/xbtree.py

@@ -371,6 +371,15 @@ def Restructure(ztree, newStructure):
     zrbucketv.sort(key = lambda rn: rn.range.klo)
     rbucketv .sort(key = lambda rn: rn.range.klo)
 
+    # verify that old keys == new keys
+    zkeys = set()
+    keys  = set()
+    for _ in zrbucketv: zkeys.update(_.node.keys())
+    for _ in  rbucketv:  keys.update(_.node.keyv)
+    assert set(kv.keys()) == zkeys
+    if zkeys != keys:
+        raise ValueError("new keys != old keys\ndiff: %s" % zkeys.symmetric_difference(keys))
+
     # chain buckets via .next_bucket
     assert len(rbucketv) > 0
     for i in range(len(rbucketv)-1):