The full integration of information retrieval (IR) features into a database management system (DBMS) has long been recognized as both a significant goal and a challenging undertaking. By full integration we mean: i) support for document storage, indexing, retrieval, and update, ii) transaction semantics, thus all database operations on documents have the ACID properties of atomicity, consistency, isolation, and durability, iii) concurrent addition, update, and retrieval of documents, and iv) database query language extensions to provide ranking for document retrieval operations. It is also necessary for the integrated offering to exhibit scaleable performance for document indexing and retrieval processes. To identify the implementation requirements imposed by the desired level of integration, we layered a representative IR application on Oracle Rdb and then conducted a number of database load and document retrieval experiments. The results of these experiments suggest that infrastructural extensions are necessary to obtain both the desired level of IR integration and scaleable performance. With the insight gained from our initial experiments, we developed an approach, called cooperative indexing, that provides a framework to achieve both scaleability and full integration of IR and RDBMS technology. Prototype implementations of system-level extensions to support cooperative indexing were evaluated with a modified version of Oracle Rdb. Our experimental findings validate the cooperative indexing scheme and suggest alternatives to further improve performance.

Since 1986 we have investigated the problems and possibilities of applying modern information retrieval methods to large online public access library catalogs (OPACs). In the Retrieval Experiment—Virginia Tech OnLine Catalog (REVTOLC) study we carried out a large pilot test in 1987 and a larger, controlled investigation in 1990, with 216 users and roughly 500,000 MARC records. Results indicated that a forms-based interface coupled with vector and relevance feedback retrieval methods would be well received. Recent efforts developing the Multiple Access and Retrieval of Information with Annotations (MARIAN) system have involved used of a specially developed object-oriented DBMS, construction of a client running under NeXTSTEP, programming of a distributed server with a thread assigned to each user session to increase concurrency on a small network of NeXTs, refinement of algorithms to use objects and stopping rules for greater efficiency, usability testing and iterative interface refinement.

Rapid access to information is essential for a wide variety of retrieval systems and applications.Hashing has long been used when the fastest possible direct search is desired, but is generally not appropriate when sequential or range searches are also required.This paper describes a hashing method, developed for collections that are relatively static, that supports both direct and sequential access.The algorithms described give hash functions that are optimal in terms of time and hash table space utilization, and that preserve any a priori ordering desired, Furthermore, the resulting order-preserving minimal perfect hash functions (OPMPHFS) can be found using time and space that are linear in the number of keys involve~this is close to optimal,

Rapid access to information is essential for a wide variety of retrieval systems and applications. Hashing has long been used when the fastest possible direct search is desired, but is generally not appropriate when sequential or range searches are also required. This paper describes a hashing method, developed for collections that are relatively static, that supports both direct and sequential access. Indeed, the algorithm described gives hash functions that are optimal in terms of time and hash table space utilization, and that preserve any a priori ordering desired. Furthermore, the resulting order preserving minimal perfect hash functions (OPMPHFs) can be found using space and time that is on average linear in the number of keys involved.