Ordered Types in the AQUA Data Model

We present a query algebra that supports ordering among the data ele ments Order is de ned as a relationship between various data elements of an instance This relationship can be a total or partial order among the elements or among equivalence classes where each equivalence class consists of one or more elements In terms of data structures ordered types can be viewed as graphs trees or lists Lately there has been a lot of interest in bulk types like lists trees and graphs that are not supported by traditional data models and query algebras This interest is fueled by the fact that much of the data in the scienti c domain is inherently ordered Therefore scienti c applications that involve genome sequences satellite data scienti c data etc require database support for ordered data structures like lists trees and graphs In this paper we discuss an extension to the AQUA query algebra to handle ordered types and their operators We show how these operators can t into a framework for query optimization