Integration of composite objects into relational query processing : the SQL/XNF approach

Complex database applications, such as design applications, multi-media and AI applications, and even enhanced business applications can benefit significantly from a database language that supports composite objects. The data used by such applications are often shared with more traditional applications, such as cost accounting, project management, etc. Hence, sharing of the data among traditional applications and complex object applications is important. Our approach, called SQL Extended Normal Form (short SQL/XNF) provides a general framework that supports novel processing models based on composite objects. Especially, it enhances relational technology by a composite object facility, which comprises not only extraction of composite objects from a shared database, but also adequate browsing and manipulation facilities provided by an appropriate application programming interface

Object-oriented query language facilitating construction of new objects

In object-oriented database systems, messages can be used to manipulate the database; however, a query language is still a required component of any kind of database system. In the paper, we describe a query language for object-oriented databases where both objects as well as behaviour defined in them are handled. Not only existing objects are manipulated; the introduction of new relationships and new objects constructed out of existing ones is also facilitated. The operations supported in the described query language subsumes those of the relational algebra aiming at a more powerful query language than the relational algebra. Among the additional operators, there is an operator that handles the application of an aggregate function on objects in an operand while still having the result possessing the characteristics of an operand. The result of a query as well as the operands are considered to have a pair of sets, a set of objects and a set of message expressions; where a message expression is a sequence of messages. A message expression handles both stored and derived values and hence provides a full computational power without having an embedded query language with impedance mismatch. Therefore the closure property is maintained by having the result of a query possessing the characteristics of an operand. Furthermore, we define a set of objects and derive a set of message expressions for every class; hence any class can be an operand. Moreover, the result of a query has the characteristics of a class and its superclass/subclass relationships with the operands are established to make it persistent. © 1993

Query model for object-oriented databases

A query language should be a part of any database system. While the relational model has a well defined underlying query model, the object-oriented database systems have been criticized for not having such a query model. One of the most challenging steps in the development of a theory for object-oriented databases is the definition of an object algebra. A formal object-oriented query model is described here in terms of an object algebra, at least as powerful as the relational algebra, by extending the latter in a consistent manner. Both the structure and the behavior of objects are handled. An operand and the output from a query in the object algebra are defined to have a pair of sets, a set of objects and a set of message expressions where a message expression is a valid sequence of messages. Hence the closure property is maintained in a natural way. In addition, it is proved that the output from a query has the characteristics of a class; hence the inheritance (sub/superclass) relationship between the operand(s) and the output from a query is derived. This way, the result of a query can be persistently placed in its proper place in the lattice

Interface design for a Chinese database system.

Lee Fu Wing.Thesis (M.Phil.)--Chinese University of Hong Kong, 1995.Includes bibliographical references (leaves 96-104).Abstract --- p.iChapter 1. --- Introduction --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.2 --- The contribution of this project --- p.3Chapter 1.3 --- Scope of Thesis --- p.3Chapter 2. --- Background Study --- p.4Chapter 2.1 --- Related works of General DBMS User Interface --- p.4Chapter 2.1.1 --- Linear System --- p.4Chapter 2.1.2 --- Form-Based System --- p.6Chapter 2.1.3 --- Other Approaches --- p.8Chapter 2.2 --- Related works of Chinese System --- p.9Chapter 2.2.1 --- Artificial Natural Language --- p.9Chapter 2.2.2 --- """Chinesized"" English Database Query Language" --- p.9Chapter 2.2.3 --- Chiq1 --- p.10Chapter 3. --- Design Principles --- p.11Chapter 3.1 --- Data Model --- p.11Chapter 3.2 --- Language Naturalness --- p.11Chapter 3.3 --- Novice Users vs Expert Users --- p.12Chapter 3.4 --- Practical Requirements --- p.14Chapter 3.4.1 --- Relational Algebra Operators --- p.15Chapter 3.4.2 --- Divide and Conquer Querying Strategy --- p.16Chapter 3.4.3 --- Unit of Operations --- p.17Chapter 3.4.4 --- Graphical User Interface (GUI) --- p.18Chapter 3.4.5 --- Direct Object Manipulation --- p.19Chapter 3.5 --- SQL Expressiveness --- p.19Chapter 4. --- Query Specification in Chinese --- p.21Chapter 4.1 --- Defining Elementary Operations --- p.21Chapter 5. --- Implementation of the System Design --- p.29Chapter 5.1 --- Hardware and Software Configuration --- p.29Chapter 5.1.1 --- Basic Components --- p.29Chapter 5.1.2 --- Procedures for Data Retrieval --- p.30Chapter 5.2 --- System Design --- p.32Chapter 5.2.1 --- Common Operations --- p.32Chapter 5.2.2 --- Select the Required Tables --- p.33Chapter 5.2.3 --- Performing Join --- p.35Chapter 5.2.4 --- Performing Restriction --- p.36Chapter 5.2.5 --- Performing Projection --- p.37Chapter 5.2.6 --- Completion of Query --- p.38Chapter 5.2.7 --- Other Basic Operations --- p.39Chapter 5.2.8 --- Set Operations --- p.40Chapter 5.2.9 --- Composing and Decomposing a Complex Query --- p.41Chapter 6. --- Query Formulation in the Interface --- p.42Chapter 6.1 --- Example 1 (Simple Query - Novice User) --- p.45Chapter 6.2 --- Example 2 (Simple Query - Expert User) --- p.65Chapter 6.3 --- Example 3 (Simple Query with Group-By Feature) --- p.77Chapter 6.4 --- Example 4 (Complex Query with Set Operations) --- p.87Chapter 7. --- Summary and Conclusions --- p.90Chapter 7.1 --- Summary of Accomplishment --- p.90Chapter 7.2 --- Future Work --- p.94Chapter 7.3 --- Conclusion --- p.95Chapter 8. --- References --- p.96Chapter 9. --- Appendix A : 66 Testing Queries --- p.105Chapter 10. --- Appendix B : Glossary --- p.112Chapter 11. --- Appendix C : Programs Listing --- p.11

A query model and an object algebra for object-oriented databases

Ankara : The Department of Computer Engineering and Information Science and the Institute of Engineering and Science of Bilkent University, 1993.Thesis (Ph. D.) -- Bilkent University, 1993.Includes bibliographical references leaves 99-109.A query model is an important component of any database system. In this sense, the relational model has a well defined underlying query model. On the other hand, a well defined query model for object-oriented databases has not been accepted yet. This is one of the common complaints against object-oriented databases. So defining a formal object algebra is one of the most challenging steps in developing a theory for object-oriented databases. In object-oriented data models, although messages serve to manipulate the database, a query model is still required to effectively deal with more complex situations and to facilitate associative access. In this thesis, a query model for object-oriented databases is described, where both the structure and the behavior of objects are handled. Not only the manipulation of existing objects, but also the creation of new objects and the introduction of new relationships are supported in the model. Equivalents to the five basic operations of the relational model as ivell as other additional operations such as one level project, nest and aggregate function application are defined. Hence, the proposed object algebra subsumes the relational algebra. Linear recursion is also supported without requiring any additional operator to serve the purpose. Both the operands as well as the results of these operations are characterized as having a pair of sets -a set of objects and a set of message expressions (sequences of messages) applicable to them. The closure property is shown to be preserved in a natural way by the results of operations possessing the same characteristics as the operands in a query. It is shown that every class possesses the properties of an operand by defining a set of objects and deriving a set of message expressions for it. Furthermore, it is shown that the output of a query has the characteristics of a class. Thus, it is also shown how the super/subclass relationships of the result of a query with its operands can be established and how the result can be placed persistently in the lattice (schema) as a class. Such a class is naturally and properly placed in the lattice by maximizing reusability due to inheritance. Also equivalent object algebra expressions are presented and the associativity of the cross-product operation which is an important property in query optimization is proved. Lastly, as it was recognized that schema evolution is an important requirement to be satisfied by object-oriented databases, hence the handling of schema evolution functions through the proposed object algebra operations is also developed as another contribution of the thesis.Al- Hajj, RedaPh.D

Object-Oriented Query Language Design and Processing

This thesis proposes an object-oriented query language that is more powerful than many existing query languages. The language is formally specified and its expressive power is demonstrated by giving four translation schemes from other prominent object-oriented query languages. Further, this query language can be supported by a query algebra and both the query language and query algebra can be optimised using meaning preserving transformation rules. Object-Oriented Query Languages. The functional requirements of high-level object-oriented query languages are identified and they combine as well as supplement features found in existing object-oriented query languages. Effectively they formulate a query model against which existing query languages can be evaluated and compared. An evaluation of four representative query languages chosen from research prototypes and commercial products shows that none satisfies all the requirements. On the basis of the requirements a new query language, object comprehensions, is developed to provide a concise, clear, powerful, and optimisable query language for object-oriented databases. Some optimisation opportunities for the novel features are identified. A set of translation schemes from the query languages studied to object comprehensions is presented. Such translations demonstrate that object comprehensions are at least as powerful as these query languages and a system supporting object comprehensions can potentially support multiple query languages by providing translations to object comprehensions. Algebraic Support. The canonical algebra provides an abstract execution engine with which object comprehension queries can be expressed using algebraic operations. The translation scheme from object comprehensions to the canonical algebra is very simple and is no for supporting queries involving mixed collection classes The canonical algebra shares many operations with other query algebras and is formally specified. A set of transformation rules that can be used for optimisation is presented whose validity can be verified given the formal specification. Formal Data Model. The data model which forms the basis of investigation is formally defined using the specification language Z. This reference data model captures all the essential features of existing object-oriented data models including multiple inheritance. However, unlike existing data models, it also supports a generalised form of method over-loading. Static type checking of such overloaded methods is studied in this thesis

Development of an advanced artificial intelligent reliability analysis tool to enhance ship operations and maintenance activities

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