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| Content Provider | ACM Digital Library |
|---|---|
| Author | Gravano, Luis Jain, Pranay Agichtein, Eugene Ipeirotis, Panagiotis G. |
| Abstract | Text is ubiquitous and, not surprisingly, many important applications rely on textual data for a variety of tasks. As a notable example, information extraction applications derive structured relations from unstructured text; as another example, focused crawlers explore the web to locate pages about specific topics. Execution plans for text-centric tasks follow two general paradigms for processing a text database: either we can scan, or 'crawl," the text database or, alternatively, we can exploit search engine indexes and retrieve the documents of interest via carefully crafted queries constructed in task-specific ways. The choice between crawl- and query-based execution plans can have a substantial impact on both execution time and output "completeness" (e.g., in terms of recall). Nevertheless, this choice is typically ad-hoc and based on heuristics or plain intuition. In this paper, we present fundamental building blocks to make the choice of execution plans for text-centric tasks in an informed, cost-based way. Towards this goal, we show how to analyze query- and crawl-based plans in terms of both execution time and output completeness. We adapt results from random-graph theory and statistics to develop a rigorous cost model for the execution plans. Our cost model reflects the fact that the performance of the plans depends on fundamental task-specific properties of the underlying text databases. We identify these properties and present efficient techniques for estimating the associated cost-model parameters. Overall, our approach helps predict the most appropriate execution plans for a task, resulting in significant efficiency and output completeness benefits. We complement our results with a large-scale experimental evaluation for three important text-centric tasks and over multiple real-life data sets. |
| Starting Page | 265 |
| Ending Page | 276 |
| Page Count | 12 |
| File Format | |
| ISBN | 1595934340 |
| DOI | 10.1145/1142473.1142504 |
| Language | English |
| Publisher | Association for Computing Machinery (ACM) |
| Publisher Date | 2006-06-27 |
| Publisher Place | New York |
| Access Restriction | Subscribed |
| Subject Keyword | Text databases Metasearching Focused crawling Information extraction Research Query optimization |
| Content Type | Text |
| Resource Type | Article |
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