Shamkant B. Navathe

MITOMAP: a human mitochondrial genome database--2004 update.

MITOMAP (http://www.MITOMAP.org), a database for the human mitochondrial genome, has grown rapidly in data content over the past several years as interest in the role of mitochondrial DNA (mtDNA) variation in human origins, forensics, degenerative diseases, cancer and aging has increased dramatically. To accommodate this information explosion, MITOMAP has implemented a new relational database and an improved search engine, and all programs have been rewritten. System administrative changes have been made to improve security and efficiency, and to make MITOMAP compatible with a new automatic mtDNA sequence analyzer known as Mitomaster.

Vertical partitioning algorithms for database design

This paper addresses the vertical partitioning of a set of logical records or a relation into fragments. The rationale behind vertical partitioning is to produce fragments, groups of attribute columns, that “closely match” the requirements of transactions. Vertical partitioning is applied in three contexts: a database stored on devices of a single type, a database stored in different memory levels, and a distributed database. In a two-level memory hierarchy, most transactions should be processed using the fragments in primary memory. In distributed databases, fragment allocation should maximize the amount of local transaction processing. Fragments may be nonoverlapping or overlapping. A two-phase approach for the determination of fragments is proposed; in the first phase, the design is driven by empirical objective functions which do not require specific cost information. The second phase performs cost optimization by incorporating the knowledge of a specific application environment. The algorithms presented in this paper have been implemented, and examples of their actual use are shown.

A theory of attributed equivalence in databases with application to schema integration

The authors present a common foundation for integrating pairs of entity sets, pairs of relationship sets, and an entity set with a relationship set. This common foundation is based on the basic principle of integrating attributes. Any pair of objects whose identifying attributes can be integrated can themselves be integrated. Several definitions of attribute equivalence are presented. These definitions can be used to specify the exact nature of the relationship between a pair of attributes. Based on these definitions, several strategies for attribute integration are presented and evaluated. >

Mining for strong negative associations in a large database of customer transactions

Mining for association rules is considered an important data mining problem. Many different variations of this problem have been described in the literature. We introduce the problem of mining for negative associations. A naive approach to finding negative associations leads to a very large number of rules with low interest measures. We address this problem by combining previously discovered positive associations with domain knowledge to constrain the search space such that fewer but more interesting negative rules are mined. We describe an algorithm that efficiently finds all such negative associations and present the experimental results.

Vertical partitioning for database design: a graphical algorithm

Vertical partitioning is the process of subdividing the attributes of a relation or a record type, creating fragments. Previous approaches have used an iterative binary partitioning method which is based on clustering algorithms and mathematical cost functions. In this paper, however, we propose a new vertical partitioning algorithm using a graphical technique. This algorithm starts from the attribute affinity matrix by considering it as a complete graph. Then, forming a linearly connected spanning tree, it generates all meaningful fragments simultaneously by considering a cycle as a fragment. We show its computational superiority. It provides a cleaner alternative without arbitrary objective functions and provides an improvement over our previous work on vertical partitioning.

A temporal relational model and a query language

Abstract This paper proposes an extension of the relational data model for incorporating temporal semantics of the real world into a database. In this temporal relational model (TRM), the attributes are categorized as synchronous and asynchronous. This categorization leads to the notions of temporal dependency and time normal form. The imposition of time normal form avoids redundancy and retrieval and update anomalies. New relational algebra operations for this model are also discussed. A temporal query language called tsql , which is a superset of sql , has been proposed to retrieve information from time-varying relations. tsql has several new features, which provide extremely powerful query processing capabilities for time-varying relations. The model and the language have numerous applications, where data in their historical form are important.

Efficient data allocation over multiple channels at broadcast servers

Broadcast is a scalable way of disseminating data because broadcasting an item satisfies all outstanding client requests for it. However, because the transmission medium is shared, individual requests may have high response times. In this paper, we show how to minimize the average response time given multiple broadcast channels by optimally partitioning data among them. We also offer an approximation algorithm that is less complex than the optimal and show that its performance is near-optimal for a wide range of parameters. Finally, we briefly discuss the extensibility of our work with two simple, yet seldom researched extensions, namely, handling varying sized items and generating single channel schedules.

Distribution Design of Logical Database Schemas

The optimal distribution of a database schema over a number of sites in a distributed network is considered. The database is modeled in terms of objects (relations or record sets) and links (predefined joins or CODASYL sets). The design is driven by user-supplied information about data distribution. The inputs required by the optimization model are: 1) cardinality and size information about objects and links, 2) a set of candidate horizontal partitions of relations into fragments and the allocations of the fragments, and 3) the specification of all important transactions, their frequencies, and their sites of origin.

Natural language query filtration in the Conceptual Query Language

Natural language (NL) interfaces for database query formulation have always been recognized as a much needed enhancement for end-users. Poor performances with earlier NL systems had led to a lull in research in this field. However, latter-day experiments and systems appear to be sufficiently more promising to warrant continued and further research in this area. This paper proposes an experimental query interface that filters NL query statements for search predicates that are derived from constructs on conceptual schemas, thereby avoiding the computational difficulty with full-fledged NL parsing. A prototype of the Conceptual Query Language (CQL) exists as a front-end to an Oracle relational DBMS.

A tool for integrating conceptual schemas and user views

An interactive tool has been developed to assist database designers and administrators (DDA) in integrating schemas. It collects the information required for integration from a DDA, performs essential bookkeeping, and integrates schemas according to the semantics provided. The authors present the capabilities of this tool by discussing the integration methodology and the user interface of the tool.<<ETX>>