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Lecture Database system concepts (6/e): Chapter 18 - Silberschatz, Korth, Sudarshan

Chapter 18 - Parallel databases. In this chapter, on parallel databases, explores a variety of parallelization techniques, including I/O parallelism, interquery and intraquery parallelism, and interoperation and intraoperation parallelism. The chapter also describes parallel-system design. | Chapter 18: Parallel Databases Database System Concepts, 6th Ed. ©Silberschatz, Korth and Sudarshan See www.db-book.com for conditions on re-use Chapter 18: Parallel Databases Introduction I/O Parallelism Interquery Parallelism Intraquery Parallelism Intraoperation Parallelism Interoperation Parallelism Design of Parallel Systems Database System Concepts - 6th Edition 18.2 ©Silberschatz, Korth and Sudarshan Introduction Parallel machines are becoming quite common and affordable Prices of microprocessors, memory and disks have dropped sharply Recent desktop computers feature multiple processors and this trend is projected to accelerate Databases are growing increasingly large large volumes of transaction data are collected and stored for later analysis. multimedia objects like images are increasingly stored in databases Large-scale parallel database systems increasingly used for: storing large volumes of data processing time-consuming decision-support queries providing high throughput for transaction processing Database System Concepts - 6th Edition 18.3 ©Silberschatz, Korth and Sudarshan Parallelism in Databases Data can be partitioned across multiple disks for parallel I/O. Individual relational operations (e.g., sort, join, aggregation) can be executed in parallel data can be partitioned and each processor can work independently on its own partition. Queries are expressed in high level language (SQL, translated to relational algebra) makes parallelization easier. Different queries can be run in parallel with each other. Concurrency control takes care of conflicts. Thus, databases naturally lend themselves to parallelism. Database System Concepts - 6th Edition 18.4 ©Silberschatz, Korth and Sudarshan I/O Parallelism Reduce the time required to retrieve relations from disk by partitioning The relations on multiple disks. Horizontal partitioning – tuples of a relation are divided among .