A Compressed Text Index on Secondary Memory

Abstract

We introduce a practical disk-based compressed text index that, when the text is compressible, takes little more than the plain text size (and replaces it). It provides very good I/O times for searching, which in particular improve when the text is compressible. In this aspect our index is unique, as compressed indexes have been slower than their classical counterparts on secondary memory. We analyze our index and show experimentally that it is extremely competitive on compressible texts.