Deadlock is the status when two transactions are both waiting for the other to release resources when they have allocated the same resources but in a different order. Consequently, processing by both transactions is stalemated and cannot proceed. Deadlock often occurs between a referencing transaction and an updating or deletion transaction. Changing the access order of the UAPs can reduce the incidence of deadlocks. When deadlock occurs during operation of HiRDB, HiRDB outputs deadlock information that includes information on deadlocks that have occurred among multiple transactions in the server. For details about preventing deadlock, see the HiRDB Version 8 UAP Development Guide.