Alan J. Kent

Multikey access methods based on superimposed coding techniques

Both single-level and two-level indexed descriptor schemes for multikey retrieval are presented and compared. The descriptors are formed using superimposed coding techniques and stored using a bit-inversion technique. A fast-batch insertion algorithm for which the cost of forming the bit-inverted file is less than one disk access per record is presented. For large data files, it is shown that the two-level implementation is generally more efficient for queries with a small number of matching records. For queries that specify two or more values, there is a potential problem with the two-level implementation in that costs may accrue when blocks of records match the query but individual records within these blocks do not. One approach to overcoming this problem is to set bits in the descriptors based on pairs of indexed terms. This approach is presented and analyzed.

Atlas: a nested relational database system for text applications

Advanced database applications require facilities such as text indexing, image storage, and the ability to store data with a complex structure. However, these facilities are not usually included in traditional database systems. In this paper we describe Atlas, a nested relational database system that has been designed for text-based applications. The Atlas query language is TQL, an SQL-like query language with text operators. The query language is supported by signature file text indexing techniques, and by a parser that can be configured for different text formats and even some foreign languages. Atlas can also be used to store images and audio. >

A signature file scheme based on multiple organizations for indexing very large text databases

A new signature file method for accessing information from large databases containing both formatted and free text data is presented. The new method, called the multiorganizational scheme is proposed for indexing very large databases containing hundreds of thousands or possibly millions of records. With this method, records are grouped into blocks and signatures are formed for each block of records. These signatures are stored in a block descriptor file using a storage device called the bit slice organization. By forming multiple block descriptor files, each based on a possibly different grouping of records into blocks, it is possible to efficiently determine record matches on query. Both computational results based on a mathematical model as well as experimental results using a library database are presented. These results show that the method provides effective access to large text databases.

Architecture of a content management server for XML document applications

Describes the data model that is used to implement the SIM content management server (CMS), an SGML/XML-native content server that is designed to support extremely fast data access to and dynamic updating of 100-GByte collections under high loads. This paper describes the requirements for supporting text-intensive applications and for building XML/SGML document management solutions. The SIM CMS employs a data model that is designed to directly support SGML and XML; this model is described, and a comparison with other models based on general-purpose database management systems is made.

Querying in a Large Hyperbase

This paper proposes a query language and data organisation for large hyperbase systems. The language allows queries to involve the links as well as the text. The architecture allows the data to be efficiently indexed, as well as supporting multiple users.

The structured information manager (SIM)

SIM, the Structured Information Manager, is an information retrieval system which is designed to manage multi-gigabyte collections of documents containing text, images, and other forms of data, storing them natively in SGML, XML, MARC, RTF, and ASCII formats. It is a fully-fledged system that provides integrated support for efficient ranked full text, boolean, and structural querying via a robust database server capable of practically managing multi-gigabyte document collections.

An environment for building graphical user interfaces for nested relational databases

Abstract This paper describes the architecture of an environment for building portable forms-based graphical user interfaces. The environment provides a particularly good platform for creating forms-based user interfaces to nested relational databases on a range of platforms, from workstations with bitmap screens to character based terminals. The major problems involved in creating these interfaces are the displaying of nested tables which would normally be larger than the available screen area, and the laying out of the elements of the forms-based interface inside the window. These problems are discussed and solutions to them are provided.