WebTables: exploring the power of tables on the web

The World-Wide Web consists of a huge number of unstructured documents, but it also contains structured data in the form of HTML tables. We extracted 14.1 billion HTML tables from Google's general-purpose web crawl, and used statistical classification techniques to find the estimated 154M that contain high-quality relational data. Because each relational table has its own "schema" of labeled and typed columns, each such table can be considered a small structured database. The resulting corpus of databases is larger than any other corpus we are aware of, by at least five orders of magnitude. We describe the WebTables system to explore two fundamental questions about this collection of databases. First, what are effective techniques for searching for structured data at search-engine scales? Second, what additional power can be derived by analyzing such a huge corpus? First, we develop new techniques for keyword search over a corpus of tables, and show that they can achiev...

• Type: Journal
• Year: 2008
• Where: PVLDB
• Authors: Michael J. Cafarella, Alon Y. Halevy, Daisy Zhe Wang, Eugene Wu 0002, Yang Zhang
• Keywords: Database, HTML Tables, PVLDB 2008, Schema Elements