ZODB.Architecture.Storage Interface.undo

Documentation
Undo the transaction corresponding to the given transaction id. This method is not state dependent. If the transaction_id cannot be undone, then an UndoError is raised.
Parameters
TypeNameDefaultDocumentation
PyStringtransaction_id a name for a transaction to be undone. The format of this name is storage dependent.
Transactiontransaction  
PyIntlimit the maximum number of object ids to return. If None is supplied, then there is no limit.
Returns
OIDsthe object IDs that were affected by the transaction that was undone. These objects should be invalidated. The return value may be None (if the number of ids exceed the limit), in which case all objects should be invalidated.
Errors
If the transaction_id cannot be undone, then an UndoError is raised.
PreConditions
All of the records in the transaction must be current wrt to their session.
State-dependent
This method is state dependent. It is only valid in the commiting state.