Non-two-phase locking protocols with shared and exclusive locks
Zvi M. Kedem, Abraham Silberschatz · Very Large Data Bases · 1980
This paper is concerned with the problem of developing a family of locking protocols which employ both SHARED and EXCLUSIVE locks and which ensure the consistency of database systems that are accessed concurrently by a number of asynchronously running transactions. The protocols in the family are not two-phase. They are applicable to database systems which are hierarchically organized as well as database systems which are modeled by directed acyclic graphs. A comparison with other previously published protocols is also presented.