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Rule Languages and Internal Algebras for RuleBased Optimizers
 In Proc. ACM SIGMOD Int'l Conference on Management of Data
, 1996
"... Rulebased optimizers and optimizer generators use rules to specify query transformations. Rules act directly on query representations, which typically are based on query algebras. But most algebras complicate rule formulation, and rules over these algebras must often resort to calling to externally ..."
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Cited by 32 (6 self)
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Rulebased optimizers and optimizer generators use rules to specify query transformations. Rules act directly on query representations, which typically are based on query algebras. But most algebras complicate rule formulation, and rules over these algebras must often resort to calling to externally defined bodies of code. Code makes rules difficult to formulate, prove correct and reason about, and therefore compromises the effectiveness of rulebased systems. In this paper we present KOLA; a combinatorbased algebra designed to simplify rule formulation. KOLA is not a user language, and KOLA's variablefree queries are difficult for humans to read. But KOLA is an effective internal algebra because its combinatorstyle makes queries manipulable and structurally revealing. As a result, rules over KOLA queries are easily expressed without the need for supplemental code. We illustrate this point, first by showing some transformations that despite their simplicity, require head and body rou...
Explicit Graphs in a Functional Model for Spatial Databases
 IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING
, 1994
"... Observing that networks are ubiquitous in applications for spatial databases, we define a new data model and query language that especially supports graph structures. This model integrates concepts of functional data modeling with ordersorted algebra. Besides object and data type hierarchies grap ..."
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Cited by 29 (9 self)
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Observing that networks are ubiquitous in applications for spatial databases, we define a new data model and query language that especially supports graph structures. This model integrates concepts of functional data modeling with ordersorted algebra. Besides object and data type hierarchies graphs are available as an explicit modeling tool, and graph operations are part of the query language. Graphs have three classes of components, namely nodes, edges, and explicit paths. These are at the same time object types within the object type hierarchy and can be used like any other type. Explicit paths are useful because “real world ” objects often correspond to paths in a network. Furthermore, a dynamic generalization concept is introduced to handle heterogeneous collections of objects in a query. In connection with spatial data types this leads to powerful modeling and querying capabilities for spatial databases, in particular for spatially embedded networks such as highways, rivers, public transport, and so forth. We use multilevel ordersorted algebra as a formal framework for the specification of our model. Roughly spoken, the first level algebra defines types and operations of the query language whereas the second level algebra defines kinds (collections of types) and type constructors as functions between kinds and so provides the types that can be used at the first level.
An Expressive Constraint Language for Semantic Web Applications
, 2001
"... We present a framework for semantic web applications based on constraint interchange and processing. At the core of the framework is a wellestablished semantic data model (P/FDM) with an associated expressive constraint language (Colan). To allow data instances to be transported across a netwo ..."
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Cited by 17 (9 self)
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We present a framework for semantic web applications based on constraint interchange and processing. At the core of the framework is a wellestablished semantic data model (P/FDM) with an associated expressive constraint language (Colan). To allow data instances to be transported across a network, we map our data model to the RDF Schema specification. To allow constraints to be transported, we define a Constraint Interchange Format (CIF) in the form of an RDF Schema for Colan, allowing each constraint to be defined as a resource in its own right. We show that, because Colan is essentially a syntacticallysugared form of firstorder logic, and P/FDM is based on the widelyused extended ER model, our CIF is actually very widely applicable and reusable. Finally, we outline a set of services for constraint fusion and solving, which are particularly applicable to businesstobusiness ecommerce applications. All of these services can be accessed using the CIF.
Algebraic Query Optimisation for Database Programming Languages
 The VLDB Journal
, 1996
"... A major challenge still facing the designers and implementors of database programming languages (DBPLs) is that of query optimisation. We investigate algebraic query optimisation for DBPLs in the context of a purely declarative functional language that supports sets as firstclass objects. Since the ..."
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Cited by 12 (4 self)
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A major challenge still facing the designers and implementors of database programming languages (DBPLs) is that of query optimisation. We investigate algebraic query optimisation for DBPLs in the context of a purely declarative functional language that supports sets as firstclass objects. Since the language is computationally complete issues such as nontermination of expressions and construction of infinite data structures can be investigated, whilst its declarative nature allows the issue of side effects to be avoided and a rich set of equivalences to be developed. The language has a welldefined semantics which permits us to reason formally about the properties of expressions, such as their equivalence with other expressions and their termination. The support of a set bulk data type enables much prior work on the optimisation of relational languages to be utilised. In the paper we first give the syntax of an archetypal DBPL and briefly discuss its semantics. We then de...
Compiling a Declarative HighLevel Language for Semantic Integrity Constraints
 Proceedings of 6th IFIP TC2 Working Conference on Data Semantics
, 1995
"... The provision of more intelligent support for complex database applications is becoming an important research topic, and declaratively stated integrity constraints are increasingly being seen as a potential source of semantic information for such advanced DBMS's. However, despite much research ..."
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Cited by 10 (9 self)
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The provision of more intelligent support for complex database applications is becoming an important research topic, and declaratively stated integrity constraints are increasingly being seen as a potential source of semantic information for such advanced DBMS's. However, despite much research e#ort, the problem of e#ciently compiling and checking a wide range of complex constraints has not yet been solved. And until it is solved, few database designers will be willing to sacrifice the performance of the every day database usage, in order to provide a complete semantic modelling of their application domain. In this paper, we describe the implementation of a constraint checking architecture and compiler, which have been designed to combine an expressive constraint language with e#cient runtime maintenance. While the current implementation does not yet achieve high e#ciency for all constraints, it has been designed with extensibility in mind and forms a solid platform from which to inv...
Investigation of Algebraic Query Optimisation for Database Programming Languages
 In Proceedings of the 20th Int'l Conference on Very Large Databases (VLDB
, 1994
"... alexQdcs.kcl.ac.uk A major challenge still facing the designers and implementors of database programming languages (DBPLs) is that of query optimisation. We investigate algebraic query optimisation techniques for DBPLs in the context of a purely declarative functional language that supports sets a ..."
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Cited by 7 (3 self)
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alexQdcs.kcl.ac.uk A major challenge still facing the designers and implementors of database programming languages (DBPLs) is that of query optimisation. We investigate algebraic query optimisation techniques for DBPLs in the context of a purely declarative functional language that supports sets as firstclass objects. Since the language is computationally complete issues such as nontermination of expressions and construction of infinite data structures can be investigated, whilst its declarative nature allows the issue of side effects to be avoided and a richer set of equivalences to be developed. The support of a set bulk data type enables much prior work on the optimisation of relational languages to be utilised. Finally, the language has a welldefined semantics which permits us to reason formally about the prop erties of expressions, such as their equivalence with other expressions and their termination. 1
An Object Based Algebra for Parallel Query Processing and Optimization
, 1992
"... The Tarski algebra provides an algebraic foundation for objectbased query languages. This is demonstrated by showing how queries expressed in a graphoriented query language (based on the functional data model) can be translated into the Tarski algebra. The graphical representation of queries in co ..."
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Cited by 4 (2 self)
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The Tarski algebra provides an algebraic foundation for objectbased query languages. This is demonstrated by showing how queries expressed in a graphoriented 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 nonmonotonic 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 functionbas...
Formalization of Advanced Map Operations
"... Maps are a fundamental metaphor in GIS. We introduce several new operations on maps that go far beyond wellknown operations like overlay or reclassification. In particular, we identify and generalize operations that are of practical interest for spatial analysis and that can be useful in many GIS a ..."
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Cited by 4 (0 self)
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Maps are a fundamental metaphor in GIS. We introduce several new operations on maps that go far beyond wellknown operations like overlay or reclassification. In particular, we identify and generalize operations that are of practical interest for spatial analysis and that can be useful in many GIS applications. We give a precise definition of these operations based on a formal model of spatial partitions. This provides a theoretical foundation for maps which also serves as a specification for implementations.