Performance measurement of some main memory database recovery algorithms

The performance of two main-memory database system (MDBS) algorithms is studied. M.H. Eich´s (Proc. of the Fifth Int. Workshop on Database Machines., Oct. 1987) and T.J. Lehman´s (Ph. D. Thesis, Univ. of Wisconsin-Madison, Aug 1986) algorithms are selected for this study. The investigation indicates that the shadow approach, as used by Eich, has some advantages over the update in-place strategy of Lehman. The shadow approach has faster response for normal transactions even though transaction commit is slower compared to update in-place approach. It is concluded that irrespective of the recovery algorithm an efficient load balancing plays an important part in the performance of the system. It is suggested that processors should be allocated to any kind of activity on a demand basis. It is discovered that individual recovery of lockable units as used in Lehman´s algorithm is a better choice since it increases the system availability after a system failure. It also allows background recovery to go in parallel to normal transaction processing