Cost based plan selection for xpath

  • Authors:

  • Haris Georgiadis;Minas Charalambides;Vasilis Vassalos

  • Affiliations:

  • Athens University of Economics and Business, Athens, Greece;Athens University of Economics and Business, Athens, Greece;Athens University of Economics and Business, Athens, Greece

  • Venue:
  • Proceedings of the 2009 ACM SIGMOD International Conference on Management of data
  • Year:
  • 2009

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Abstract

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 experimentally demonstrate the effectiveness of our end-to-end query optimization system.