Allow the namespace column to be null, and also non-unique. Fix the uncompressed size clobbering the size on the wire field. Add metadata constraints so that foreign key constraints get predictable names. Fix all downgrade migrations.

data/model/sqlalchemybridge.py

@@ -17,7 +17,12 @@ OPTION_TRANSLATIONS = {
 
 
 def gen_sqlalchemy_metadata(peewee_model_list):
-  metadata = MetaData()
+  metadata = MetaData(naming_convention={
+    "ix": 'ix_%(column_0_label)s',
+    "uq": "uq_%(table_name)s_%(column_0_name)s",
+    "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
+    "pk": "pk_%(table_name)s"
+  })
 
   for model in peewee_model_list:
     meta = model._meta