A Search Engine Accepting On-Line Updates

We describe and evaluate the performance of a parallel search engine that is able to cope efficiently with concurrent read/write operations. Read operations come in the usual form of queries submitted to the search engine and write ones come in the form of new documents added to the text collection in an on-line manner, namely the insertions are embedded into the main stream of user queries in an unpredictable arrival order but with query results respecting causality. The search engine is built upon distributed inverted files for which we propose generic strategies for load balance and concurrency control.