Please use this identifier to cite or link to this item:
Title: Xplus: A SQL-Tuning-Aware Query Optimizer
Authors: Herodotou, Herodotos 
Babu, Shivnath 
Keywords: SQL;Xplus
Category: Electrical Engineering - Electronic Engineering - Information Engineering
Field: Engineering and Technology
Issue Date: 2010
Publisher: VLDB Endowment
Source: Proceedings of the VLDB Endowment VLDB Endowment Hompage archive vol. 3 no. 1-2, September 2010 pp. 1149-1160
Journal: Proceedings of the VLDB Endowment
Abstract: The need to improve a suboptimal execution plan picked by the query optimizer for a repeatedly run SQL query arises routinely. Complex expressions, skewed or correlated data, and changing conditions can cause the optimizer to make mistakes. For example, the optimizer may pick a poor join order, overlook an important index, use a nested-loop join when a hash join would have done better, or cause an expensive, but avoidable, sort to happen. SQL tuning is also needed while tuning multi-tier services to meet service-level objectives. The difficulty of SQL tuning can be lessened considerably if users and higher-level tuning tools can tell the optimizer: "I am not satisfied with the performance of the plan p being used for the query Q that runs repeatedly. Can you generate a (δ%) better plan?" This paper designs, implements, and evaluates Xplus which, to our knowledge, is the first query optimizer to provide this feature. Xplus goes beyond the traditional plan-first-execute-next approach: Xplus runs some (sub)plans proactively, collects monitoring data from the runs, and iterates. A nontrivial challenge is in choosing a small set of plans to run. Xplus guides this process efficiently using an extensible architecture comprising SQL-tuning experts with different goals, and a policy to arbitrate among the experts. We show the effectiveness of Xplus on real-life tuning scenarios created using TPC-H queries on a PostgreSQL database.
ISSN: 2-s2.0-84859229821
DOI: 10.14778/1920841.1920984
Rights: Copyright 2010 VLDB Endowment
Type: Conference Papers
Appears in Collections:Άρθρα/Articles

Show full item record


checked on Sep 19, 2019

Page view(s) 50

Last Week
Last month
checked on Sep 22, 2019

Google ScholarTM



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.