CPU and incremental memory allocation In dynamic parallelization of SQL queries

摘要

In order to re-adjust the parallel execution of SQL queries in case of metric estimation or Discretization errors, we propose an incremental parallelization method which carries out si- Multaneously both scheduling and mapping in co-operation with two incremental memory al- Location heuristics (ParAd: parallelism degree adjustment, and MaCRelax: mapping clues Relaxation) in a dynamic multi-user context. The two incremental memory allocation heuristics Are integrated in the mapping method which attempt to avoid time-consuming multi-bucket Join execution generating numerous additional I/O.