Cost based plan selection for xpath

We present a complete XPath cost-based optimization and execution framework and demonstrate its effectiveness and efficiency for a variety of queries and datasets. The framework is based on a logical XPath algebra with novel features and operators and a comprehensive set of rewriting rules that together enable us to algebraically capture many existing and novel processing strategies for XPath queries. An important part of the framework is PSA, a very efficient cost-based plan selection algorithm for XPath queries. In the presented experimental evaluation, PSA picked the cheapest estimated query plan in 100% of the cases. Our cost-based query optimizer independent of the underlying physical data model and storage system and of the available logical operator implementations, depending on a set of well-defined APIs. We also present an implementation of those APIs, including primitive access methods, a large pool of physical operators, statistics estimators and cost models, and experiment...

• Type: Conference
• Year: 2009
• Where: SIGMOD
• Authors: Haris Georgiadis, Minas Charalambides, Vasilis Vassalos
• Keywords: Cheapest Estimated Query, Database, Logical Xpath Algebra, SIGMOD 2009, XPATH Queries