Bubba is a highly parallel computer system for data-intensive applications. The basis of the Bubba design is a scalable shared-nothing architecture which can scale up to thousands of nodes. Data are declustered across the nodes (i.e. horizontally partitioned via hashing or range partitioning) and operations are executed at those nodes containing relevant data. In this way, parallelism can be exploited within individual transactions as well as among multiple concurrent transactions to improve throughput and response times for data-intensive applications. The current Bubba prototype runs on a commercial 40-node multicomputer and includes a parallelizing compiler, distributed transaction management, object management, and a customized version of Unix. The current prototype is described and the major design decisions that went into its construction are discussed. The lessons learned from this prototype and its predecessors are presented.>

The availability of larger RAM spaces for DBMSs provides interesting opportunities for performance enhancements, especially in buffer management. In this paper we propose and compare two alternative strategies for the buffer management of permanent data (i.e., the data committed by transactions) called block buffering and attribute buffering. These strategies use statistics to capture the changing locality of a reference string. We model and demonstrate the impact of locality on the performance of buffering. We also analyze and compare the effect of both the attribute and predicate dimensions of locality on buffering, varying a number of parameters including the degree of locality, RAM size, and RAM utilization.