TopX 2.0 at the INEX 2008 Efficiency Track A (Very) Fast Object-Store for Top-k-Style XML Full-Text Search

摘要

For the INEX Efficiency Track 2008, we were just on time to finish and evaluate our brand-new TopX 2.0 prototype. Complementing our long-running effort on efficient top-k query processing on top of a relational back-end, we now switched to a compressed object-oriented storage for text-centric XML data with direct access to customized inverted files, along with a complete reim-plementation of the engine in C++. Our INEX 2008 experiments demonstrate efficiency gains of up to a factor of 30 compared to the previous Java/JDBC-based TopX 1.0 implementation over a relational back-end. TopX 2.0 achieves overall runtimes of less than 51 seconds for the entire batch of 568 Efficiency Track topics in their content-and-structure (CAS) version and less than 29 seconds for the content-only (CO) version, respectively, using a top-15, focused (i.e., non-overlapping) retrieval mode-an average of merely 89 ms per CAS query and 49 ms per CO query.