An apparatus is provided for performing a method (Fig. 2) for pruning an ind ex of a corpus of text documents, wherein the method includes steps for ranking (50) the postings in the index and pruning (48) from the index the postings below a given level in the ranking. The pruning methods of the invention are lossy, since some document postings are removed from the full index; however , the user cannot differentiate the lossy index from the full index.
