Persistent cache in a distributed search engine

The Cooperative Search Engine (CSE) is a distributed search engine, which can update indexes in very short time for the purpose of fresh information retrieval in an intranet. In CSE, the retrieval performance is dependent on cache contents because communication delay occurs at retrieval time. On the other hand however, cache is invalidated as soon as indexes are updated. Therefore, we need persistent cache that can hold valid data before and after updating. In this paper, we describe the principle and evaluations of persistent cache.