Invalidating any existing session

normally handles the work of “begin” transparently, which in turn relies upon the Python DBAPI to transparently “begin” transactions; there is no need to explcitly begin transactions when using modern are specified.A “subtransaction” is essentially a code embedding pattern that does not affect the transactional state of the database connection unless a rollback is emitted, in which case the whole transaction is rolled back.

To expire all objects in the object’s current transactional context in order to load all expired attributes for the given instance.Please read the list of caveats at Perform a bulk save of the given list of objects.The bulk save feature allows mapped objects to be used as the source of simple INSERT and UPDATE operations which can be more easily grouped together into higher performing “executemany” operations; the extraction of data from the objects is also performed using a lower-latency process that ignores whether or not attributes have actually been modified in the case of UPDATEs, and also ignores SQL expressions.The “partial rollback” state refers to when an “inner” transaction, typically used during a flush, encounters an error and emits a rollback of the DBAPI connection.

At this point, the block as long as it doesn’t enter “partial rollback” state.

Altering a relationship-bound attribute on the target object may not fire off a backref event, if the effective value is what was already loaded from a foreign-key-holding value.