Comparison of Partitioning Techniques(Cont.) Round robin: Best suited for sequential scan of entire relation on each query. All nodes have almost an equal number of tuples;retrieval work is thus well balanced between nodes. All queries must be processed at all nodes Hash partitioning: Good for sequential access Assuming hash function is good,and partitioning attributes form a key, tuples will be equally distributed between nodes Good for point queries on partitioning attribute Can lookup single node,leaving others available for answering other queries. Range queries inefficient,must be processed at all nodes Database System Concepts-7th Edition 21.9 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 21.9 ©Silberschatz, Korth and Sudarshan th Edition Comparison of Partitioning Techniques (Cont.) Round robin: ▪ Best suited for sequential scan of entire relation on each query. • All nodes have almost an equal number of tuples; retrieval work is thus well balanced between nodes. ▪ All queries must be processed at all nodes Hash partitioning: ▪ Good for sequential access • Assuming hash function is good, and partitioning attributes form a key, tuples will be equally distributed between nodes ▪ Good for point queries on partitioning attribute • Can lookup single node, leaving others available for answering other queries. ▪ Range queries inefficient, must be processed at all nodes