This paper deals with the problem of scheduling spawned tasks when a query
is issued to a database which resides on a MIMD multiprocessor. These tasks
have the property that their associated dependency scheme can be presented
as a directed tree. We present a theoretical framework with extensive expe
rimental simulations which increase the throughput of database applications
. We derive a family of algorithms for scheduling tasks, Their performance
is tested on several common multiprocessor configurations. For better perfo
rmance the adaptation of the scheduling algorithm to the multiprocessor con
figuration is examined and analyzed.
The scheduling algorithms are divided into two cases: (a) permitted changes
in the resources connection scheme of the multiprocessor, and (b) no chang
es allowed. The algorithms are scalable and their complexity is computed. I
n particular, we present an algorithm for scheduling tasks in the case wher
e the construction of a central storage location is permitted. One of the m
ain tools for the construction of the above algorithms is the notion of (t,
1)-domination and k-domination sets. Copyright (C) 1999 John Wiley & Sons,
Ltd.