Starburst's eXtended Normal Form (XNF) is based upon the concept of a relational view.
An
XNF query is identified by the keywords OUT OF and consists of : 1) definitions of components tables (called 'nodes'), identified by the keyword SELECT; and 2) definitions of directed relationships (called 'edges') between component nodes (identified by the keywords RELATE <nodes> WHERE <predicates>.
XNF objects may be combined, proejcted, and restricted.
To process XNF queries, Starburst's extensible query processor also had to be extended.
Recently, we have implemented techniques for updating XNF views, including those containing joins [55]; similar techniques were independently developed in [9].