There is a growing need to develop tools that are able to retrieve relevant textual information rapidly, to present textual information in a meaningful way, and to integrate textual information with related data retrieved from other sources. These tools are critical to support applications within corporate intranets and across the rapidly evolving World Wide Web. This paper introduces a framework for modelling structured text and presents a small set of operations that may be applied against such models. Using these operations structured text may be selected, marked, fragmented, and transformed into relations for use in relational and object-oriented database systems. The extended functionality has been accepted for inclusion within the SQL/MM standard, and a prototype database engine has been implemented to support SQL with the proposed extensions. This prototype serves as a proof of concept intended to address industrial concerns, and it demonstrates the power of the proposed abstrac...

Text databases are becoming increasingly important in business applications. However the diverse nature of text is not widely understood, nor appreciated. Some properties of simple document models and text algebras are presented, and these are briefly related to conventional relational systems. 1 Text as a string The simplest view of text is as a string of characters. Such a string has the property of linear order, but imposes no other constraints. Each character in the text can be identified by its position within the character sequence (i.e., the offset from the start of the text), and substrings can be identified by the positions of their first and last characters. Text matching, then, requires finding substrings that satisfy given predicates, whether for exact match or approximate match, and returning the character positions of the start and end of the matches. Proximity matching can be applied by comparing the character offsets of substrings' endpoints as appropriate. Although e...