Multi-level locking with deadlock avoidance

The existence of multiple levels of resources in data base systems presents a problem when resources must be shared among contending users. For example, some users may be interested in an entire file while others are only interested in one or a few records of the file. Intention locks have previously been introduced to permit multiple levels of locking in conjunction with deadlock detection methods[1,2]. These intention locks can be view as housekeeping entries to record the pattern of usage of resources. When viewed in this way, no new locking modes need be exposed to a system user. Further, the basic idea behind intention locks can then be directly applied to systems which use deadlock avoidance methods[3,4].