This paper argues that comprehensions, a construct found in some programming languages, are a good query notation for DBPLs. It is shown that, like many other query notations, comprehensions can be smoothly integrated into DBPLs and allow queries to be expressed clearly, concisely and efficiently. More significantly, two advantages of comprehensions are demonstrated. The first advantage is that, unlike conventional notations, comprehension queries combine computational power with ease of optimisation. That is, not only can comprehension queries express both recursion and computation, but equivalent comprehension transformations exist for all of the major conventional optimisations. The second advantage is that comprehensions provide a uniform notation for expressing and performing some optimisation on queries over several bulk data types. The bulk types that comprehensions can be defined over include sets, relations, bags and lists. A DBPL can also be automatically extended to provide and partially optimise comprehension queries over new bulk types constructed by the application programmer, providing that the new type has some well-defined properties. 1

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A Functional Database Phil Trinder D.Phil. Thesis Wolfson College Michaelmas Term, 1989 This thesis explores the use of functional languages to implement, manipulate and query databases. Implementing databases. A functional language is used to construct a database manager that allows efficient and concurrent access to shared data. In contrast to the locking mechanism found in conventional databases, the functional database uses data dependency to provide exclusion. Results obtained from a prototype database demonstrate that data dependency permits an unusual degree of concurrency between operations on the data. The prototype database is used to exhibit some problems that seriously restrict concurrency and also to demonstrate the resolution of these problems using a new primitive. The design of a more realistic database is outlined. Some restrictions on the data structures that can be used in a functional database are also uncovered. Manipulating databases. Functions over the database a...

Abstract. A wide-area sensor system is a complex, dynamic, resource-rich collection of Internet-connected sensing devices. In this paper, we propose X-Tree Programming, a novel database-centric programming model for wide-area sensor systems designed to achieve the seemingly conflicting goals of expressiveness, ease of programming, and efficient distributed execution. To demonstrate the effectiveness of X-Tree Programming in achieving these goals, we have incorporated the model into IrisNet, a shared infrastructure for wide-area sensing, and developed several widely different applications, including a distributed infrastructure monitor running on 473 machines worldwide. 1

This paper presents an equational formulation of an objectoriented data model. In this model, a database is represented as a system of equations over a set of oid’s, and a database query is a transformation of a system of equations into another system of equations. During the query processing, our model maintains an equivalence relation over oid’s that relates oid’s corresponding to the same “real-world entity. ” By this mechanism, the model achieves a declarative set-based query language and views for objects with identity. Moreover, the query primitives are designed so that queries including object traversal can be evaluated in a data-parallel fashion. 1

The Tarski algebra provides an algebraic foundation for object-based query languages. This is demonstrated by showing how queries expressed in a graph-oriented query language (based on the functional data model) can be translated into the Tarski algebra. The graphical representation of queries in combination with the Tarski algebra is a convenient mechanism to study optimization in the context of object based query languages. We then propose extensions to the Tarski algebra that facilitate parallel query processing and address the issue of parallel query optimization in this algebraic framework. We also show how our framework helps in the study of non-monotonic query optimization. 1 Introduction Over the last decade, a variety of new database models [10] have been introduced to deal with data applications involving objects with a complex external and/or internal structure. These database models can be classified into three main categories: the complex object models, the function-bas...

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