Path expressions for complex queries and automatic database program conversion

Our efforts to develop an automatic database system conversion facility yielded a powerful, yet simple query language which was designed for ease of conversion. The path expression of this query language is a convenient and appealing notation for describing complex traversals with multiple boolean qualifications. This paper describes the path expression, shows how automatic conversions can be done, introduces the boolean functions as part of the basic path expression, offers four extensions (path macros, implied path, path replacement, and path optimization), and discusses some implementation issues.