[Checkins] SVN: zope.sqlalchemy/trunk/src/zope/sqlalchemy/datamanager.py added attention note related to savepoints in the context of Postgres 7.X

[Andreas Jung]

Log message for revision 94457:
  added attention note related to savepoints in the context of Postgres 7.X
  

Changed:
  U   zope.sqlalchemy/trunk/src/zope/sqlalchemy/datamanager.py

-=-
Modified: zope.sqlalchemy/trunk/src/zope/sqlalchemy/datamanager.py
===================================================================
--- zope.sqlalchemy/trunk/src/zope/sqlalchemy/datamanager.py	2009-01-02 19:05:24 UTC (rev 94456)
+++ zope.sqlalchemy/trunk/src/zope/sqlalchemy/datamanager.py	2009-01-02 19:06:14 UTC (rev 94457)
@@ -93,6 +93,12 @@
     def savepoint(self):
         """Savepoints are only supported when all connections support subtransactions
         """
+
+        # ATT: the following check is weak since the savepoint capability 
+        # of a RDBMS also depends on its version. E.g. Postgres 7.X does not
+        # support savepoints but Postgres is whitelisted independent of its
+        # version. Possibly additional version information should be taken
+        # into account (ajung)
         if set(engine.url.drivername
                for engine in self.session.transaction._connections.keys()
                if isinstance(engine, Engine)