Adaptive Aggregation on Chip Multiprocessors

The recent introduction of commodity chip multiprocessors requires that the design of core database operations be care-fully examined to take full advantage of on-chip parallelism. In this paper the authors examine aggregation in a multi-core environment, the Sun UltraSPARC T1, a chip multiprocessor with eight cores and a shared L2 cache. Aggregation is an important aspect of query processing that is seemingly easy to understand and implement. The research, however, demonstrates that a chip multiprocessor adds new dimensions to understanding hash-based aggregation performance concurrent sharing of aggregation data structures and contentious accesses to frequently used values.