[session] call rollback in Connection.__exit__
If we just free the cnxset and clear the Connection, we're missing the
pending operation's rollback_event callbacks, which may be needed for
cleanup.
Schema of the data
------------------
First take a look at the data schema_ then try to remember that you are browsing
through a heap of data by applying stylesheets to the results of queries. This
site is not a content management system with items placed in folders. It is an
interface to a database which applies a view to retreived data.
.. _schema: schema