Encapsulation of parallelism in the Volcano query processing system
SIGMOD '90 Proceedings of the 1990 ACM SIGMOD international conference on Management of data
Parallel database systems: the future of high performance database systems
Communications of the ACM
Distributed and parallel database systems
ACM Computing Surveys (CSUR)
Database tuning: principles, experiments, and troubleshooting techniques
Database tuning: principles, experiments, and troubleshooting techniques
Database Architecture Optimized for the New Bottleneck: Memory Access
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
Evaluating MapReduce for Multi-core and Multiprocessor Systems
HPCA '07 Proceedings of the 2007 IEEE 13th International Symposium on High Performance Computer Architecture
Pro T-SQL 2008 Programmers Guide
Pro T-SQL 2008 Programmers Guide
SQL Server 2008 Query Performance Tuning Distilled
SQL Server 2008 Query Performance Tuning Distilled
Stethoscope: a platform for interactive visual analysis of query execution plans
Proceedings of the VLDB Endowment
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Query parallelism improves serial query execution performance by orders of magnitude. Getting optimal performance from an already parallelized query plan is however difficult due to its dependency on run time factors such as correct operator scheduling, memory pressure, disk io performance, and operating system noise. Identifying the exact problems in a parallel query execution is difficult due to inter-dependence of these factors. In this paper we present Tomograph, a tool to visualize the parallel query execution performance bottlenecks. Tomograph provides a time ordered view of operator execution aligned with cpu, memory, and disk IO usage, in an operator at a time execution model. We discuss the usage of Tomograph to identify parallelism issues such as low multi-core utilization, erroneous operator scheduling, incorrect data partitioning, and blocking operators. We share our experiences, insights gained and discuss possible solutions to the identified problems.