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No description available.

No description available.

No description available.

The goal of this work is to present an advanced query processing algorithm formulated and developed in support of heterogeneous distributed database management systems. Heterogeneous distributed database management systems view the integrated data through an uniform global schema. The query processing algorithm described here produces an inexpensive strategy for a query expressed over the global schema. The research addresses the following aspects of query processing: (1) Formulation of a low level query language to express the fundamental heterogeneous database operations; (2) Translation of the query expressed over the global schema to an equivalent query expressed over a conceptual schema; (3) An estimation methodology to derive the intermediate result sizes of the database operations; (4) A query decomposition algorithm to generate an efficient sequence of the basic database operations to answer the query. This research addressed the first issue by developing an algebraic query language called cluster algebra. The cluster algebra consists of the following operations: (a) Selection, union, intersection and difference, which are extensions of their relational algebraic counterparts to heterogeneous databases; (b) Normal-join and normal-projection which replace their counterparts, join and projection, in the relational algebra; (c) Two new operators embed and unembed to restructure the database schema. The second issue of the query translation was addressed by development of an algorithm that translates a cluster algebra query expressed over the virtual views to an equivalent cluster algebra query expressed over the conceptual databases. A non-parametric estimation methodology to estimate the result size of a cluster algebra operation was developed to address the third issue described above. Finally, this research developed a query decomposition algorithm, applicable to the relational and non-relational databases, that decomposes a query by computing all profitable semi-join operations, followed by the determination of the best sequence of join operations per processing site. The join optimization is performed by formulating a zero-one integer linear program that uses the non-parametric estimation technique to compute the sizes of intermediate results. The query processing algorithm was implemented in the context of DAVID, a heterogeneous distributed database management system. / Ph. D.

Although some success has been achieved in the design of front-end natural language processors to data base management systems, transporting the processor to various data base management systems has proven to be elusive. A transportable system must be modular; it must be able to adapt to radically different data domains; and it must be able to communicate with many different data managers. The system developed accomplishes this by maintaining its own knowledge base distinct from the target data base management system, so that no communication is needed between the natural language processor and the data manager during the parse. The knowledge base is developed by interviewing the system administrator about the structure and meaning of the elements in the target data base. The natural language processor then converts the natural language query into an unambiguous intermediate-language query, which is easily converted to P the target query language using simple syntactic methods. / Master of Science

The representation of information in modern database systems is complicated by the need to represent relationships among pieces of information. A natural representation for such databases is the information graph that associates the pieces of information with vertices in the graph and the relationships with edges. Five characteristics of this representation are noteworthy. First, each vertex has a size (in bytes) sufficient to store its corresponding piece of information. Second, retrieval in an information graph may follow a number of patterns; in particular, retrieval of adjacent vertices via edge traversals must be efficient. Third, in many applications such as a dictionary or bibliographic archive, the information graph may be considered static. Fourth, the ultimate home for an information graph is likely to be a roughly linear medium such as a magnetic disk or CD-ROM. Finally, information graphs are quite large-hundreds of thousands of vertices and tens of megabytes in size. / Master of Science

A typical application for an electronic autobalance is discussed, and the requirements for an autobalance automation system are developed. The design of six application programs that satisfy these requirements is presented, and the operation and interaction of these programs is discussed in detail. Typical weighing sessions of the autobalance while running under the automation system are described. Current status of the autobalance automation system is outlined, and recommendations for future action are made. / Master of Science

Fully transportable natural language interfaces to database management systems (DBMS) have been under study for some years I but until now I all have suffered from a lack of response ability and lack of natural language update ability. Response generation is relatively easy to overcome, but the second problem, lack of update ability, is more serious. Adding update capacity involves primarily three tasks. First, the system must be able to recognize and process update requests. Processing an update typically involves both altering the knowledge base to reflect the new state of the database and performing dynamic extensions to the lexicon. Second, the intermediate language used to communicate with the database manager must be extended to cover update information. Third, the post-processor must be extended to transform commands into DBMS update requests. The system described here uses a flexible and unified knowledge base to recognize and process update requests. Through information stored in the knowledge base, the system can recognize and resolve certain classes of ambiguity. The update request is then converted into an unambiguous intermediate query language. This language is easily translated to the target database management language using simple syntactic methods. The response generator uses the intermediate query language, the knowledge base I and the results returned by the target DBMS to form a response for all database accesses. / Master of Science

Systems are developed to fulfill certain requirements. Several system design configurations usually can fulfill the technical requirements, but at different equivalent life-cycle costs. The problem is how to manipulate and evaluate different system configurations so that the required system effectiveness can be achieved at a minimum equivalent cost. It is also important to have a good definition of all the major consequences of each design configuration. For each alternative configuration considered, it is useful to know the number of units to deploy, the inventory and other logistic requirements, as well as the sensitivity of the system to changes in input variable values. An intelligent relational database management system is defined to solve the problem described. Table structures are defined to maintain the required data elements and algorithms are constructed to manipulate the data to provide the necessary information. The methodology is as follows: Customer requirements are analyzed in functional terms. Feasible design alternatives are considered and defined as system design configurations. The reliability characteristics of each system configuration are determined, initially from a system-level allocation, and later determined from test and evaluation data. A maintenance analysis is conducted to determine the inventory requirements (using reliability data) and the other logistic requirements for each design configuration. A vector of effectiveness measures can be developed for each customer, depending on objectives, constraints, and risks. These effectiveness measures, consisting of a combination of performance and cost measures, are used to aid in objectively deciding which alternative is preferred. Relationships are defined between the user requirements, the reliability and maintainability of the system, the number of units deployed, the inventory level, and other logistic characteristics of the system. A heuristic procedure is developed to interactively manipulate these parameters to obtain a good solution to the problem with technical performance and cost measures as criteria. Although it is not guaranteed that the optimal solution will be found, a feasible solution close to the optimal will be found. Eventually the user will have, at any time, the ability to change the value of any parameter modeled. The impact on the total system will subsequently be made visible. / Master of Science