Why use a Massively Parallel Processing (MPP) hardware architecture?
Is there an advantage in MPP? A. There are significant advantages in an MPP architecture for processing the complex queries which characterize the data warehouse application market. These queries are quite different from those in transaction processing. They often touch large amounts of data, are therefore normally quite I/O intensive, and they often run for very long times. They freely use SQL operators such as joins and aggregations which require processing large numbers of inter-row relationships, and thus have much poorer cache behavior than transactions. The result is that an architecture such as MPP, which isolates processor caches, scales much better than Symmetrical Multi-Processing (SMP) for this workload. Secondly, 32-bit processors are limited to addressing 4GB of memory; a tightly coupled SMP is also limited. Each processor in an MPP can address 4GB however, therefore much larger memories can be configured. Third, the intensive I/O activity in these applications must compet
