Object-Relational Database Representations for Text Indexing

One of the distinctive features of Information Retrieval systems com- paring to Database Management systems, is that they offer better compression for posting lists, resulting in better I/O performance and t hus faster query eval- uation. In this paper, we introduce database representatio ns of the index that re- duce the size (and thus the disk I/Os) of the posting lists. Th is is not achieved by redesigning the DBMS, but by exploiting the non 1NF features that exist- ing Object-Relational DBM systems (ORDBMS) already offer. Specifically, four different database representations are described and deta iled experimental results for one million pages are reported. Three of these representations are one order of magnitude more space efficient and faster (in query evalua tion) than the plain relational representation.