Update transactions

Update transactions are used for storing a limited number of database entries (instances and indexes) in a transaction in order to improve performance. Typically, update transactions are used in copy processes, where instances or indexes are accessed several times.

When the maximum number of instances is reached, the transaction buffer is emptied, i.e. transactions are written to database. One may rollback an update transaction, but this does not make much sense, since one never knows to which extent database entries have already been written to the database.