An information retrieval system uses phrases to index, retrieve, organize and describe documents. Phrases are extracted from the document collection. Documents are the indexed according to their included phrases, using phrase posting lists. The phrase posting lists are stored in an cluster of index servers....http://www.google.se/patents/US7925655?utm_source=gb-gplus-sharePatent US7925655 - Query scheduling using hierarchical tiers of index servers
Query scheduling using hierarchical tiers of index servers
