Some recent trends in business and manufacturing hold the promise of greater profits, yet, due to profit-robbing inventory increases, this promise has not been fully realized. [9] The major trends influencing this are:.

Infomaster is an information integration system that provides integrated access to multiple distributed heterogeneous information sources on the Internet, thus giving the illusion of a centralized, homogeneous information system. We say that Infomaster creates a virtual data warehouse. The core of Infomaster is a facilitator that dynamically determines an efficient way to answer the user's query using as few sources as necessary and harmonizes the heterogeneities among these sources. Infomaster handles both structural and content translation to resolve differences between multiple data sources and the multiple applications for the collected data. Infomaster connects to a variety of databases using wrappers, such as for Z39.50, SQL databases through ODBC, EDI transactions, and other World Wide Web (WWW) sources. There are several WWW user interfaces to Infomaster, including forms based and textual. Infomaster also includes a programmatic interface and it can download results in structured form onto a client computer. Infomaster has been in production use for integrating rental housing advertisements from several newspapers (since fall 1995), and for meeting room scheduling (since winter 1996). Infomaster is also being used to integrate heterogeneous electronic product catalogs.

In this work we address the problem of dealing with data inconsistencies while integrating data sets derived from multiple autonomous relational databases. The fundamental assumption in the classical relational model is that data is consistent and hence no support is provided for dealing with inconsistent data. Due to this limitation of the classical relational model, the semantics for detecting, representing, and manipulating inconsistent data have to be explicitly encoded in the applications by the application developer. In this paper, we propose the flexible relational model, which extends the classical relational model by providing support for inconsistent data. We present a flexible relation algebra, which provides semantics for database operations in the presence of potentially inconsistent data. Finally, we discuss issues raised for query optimization when the data may be inconsistent.>

We describe a two-level client-side cache for composite objects mapped as views of a relational database. A semantic model, the Structural Model, is used to specify joins on the relational database that are useful for defining composite objects. The lower level of the cache contains the tuples from each relation that have already been loaded into memory. These tuples are linked together from relation to relation according to the joins of the structural model. This level of the cache is shared among all applications using the data on this client. The higher level of the cache contains composed objects of data extracted from the lower level cache. This level of the cache uses the object schema of a single application, and the data is copied from the lower level cache for convenient access by the application. This two-level cache is designed as part of the Penguin system, which supports multiple applications, each with its own object schema, to share data stored in a common relational database.>

We describe a numbering scheme for versions with alternatives that has a useful lexicographical ordering. The version hierarchy is a tree. By inspection of the version numbers, we can easily determine whether one version is an ancestor of another. If so, we can determine the version sequence between these two versions. If not, we can determine the most recent common ancestor to these two versions (i.e., the least upper bound, lub). Sorting the version numbers lexicographically results in a version being followed by all descendants and preceded by all its ancestors. We use a representation of nonnegative integers that is self delimiting and whose lexicographical ordering matches the ordering by value.>

Building object-oriented applications which access relational data introduces a number of technical issues for developers who are making the transition to C++. We describe these issues and discuss how we have addressed them in Persistence, an application development tool that uses an automatic code generator to merge C++ applications with relational data. We use client-side caching to provide the application program with efficient access to the data.

The view-object model provides a formal basis for representing and manipulating object-based views on relational databases.

article Free AccessComment on Bancilhon and Spyratos' “Update semantics and relational views” Author: Arthur M. Keller The University of Texas at Austin, Department of Computer Sciences, Austin, TX The University of Texas at Austin, Department of Computer Sciences, Austin, TXView Profile Authors Info & Claims ACM Transactions on Database SystemsVolume 12Issue 3Sept. 1987 pp 521–523https://doi.org/10.1145/27629.214296Published:01 September 1987Publication History 14citation339DownloadsMetricsTotal Citations14Total Downloads339Last 12 Months5Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Purpose. This paper defines a layered functional architecture that is useful for describing interfaces (data or parameter exchanges) between Ada and Data Management Systems (DMS). It uses this architecture in discussing potential approaches to implementating standard interfaces between Ada and both relational and CODASYL DMSs.

When considering using databases to represent incomplete information, the relationship between two facts where one may imply the other needs to be addressed. In relational databases, this question becomes whether null completion is assumed. That is, does a (possibly partially-defined) tuple imply the existence of tuples that are ‘less informative’ than the original tuple. We show that no relational algebra, that assumes equivalence under null completion, can include set-theoretic operators that are compatible with ordinary set theory. Thus, the approach of x-relations is incompatible with the axioms of a boolean algebra.

We consider the problem of updating databases through views composed of selections?projections.and joins of a series of Boyce-Codd Normal Form relations.This involves translating updates expressed against the view to updates expressed against the database.We; present five criteria that these translations must satisfy.For each type of view update (insert.delete, replace).we provide a list of templates for translation into database updates that satisfy the five criteria.We show that there cannot be any other translations that satisfy the five criteria.KEYWORDS.Relational databases?database theory.view update.CR CATEG~!RIES.H

In this paper we consider approaches to updating databases containing null values and incomplete information. Our approach distinguishes between modeling incompletely known worlds and modeling changes in these worlds. As an alternative to the open and closed world assumptions, we propose the expanded closed world assumption. Under this assumption, we discuss how to perform updates on databases containing set nulls, marked nulls, and simple conditional tuples, and address some issues of refining incompletely specified information.

In this paper we consider approaches to updating databases containing null values and incomplete information. Our approach distinguishes between modeling incompletely known worlds and modeling changes in these worlds. As an alternative to the open and closed world assumptions, we propose the modified closed world assumption. Along with the discussion of updating, we address some issues of refining incompletely specified information.

We define the notion of independent views to indicate whether the range values of the two views may be achieved independently The concept of complementary views indicates when the domain element can be uniquely determined by the range values of the two complementary views We consider the relationship between independent and complementary views In unrestricted domains, a view (but not the identity or empty view) can have more than one complementary, independent view Databases, however, are more restricted domains They are finite power sets A view is monotonic if it preserves inclusion However, in finite power sets when all views are monotonic, if a given view has another view which is independent and complementary, then this view is unique.

A file access system, flash, for use in building database systems is described. It supports access from several languages, including pascal, fortran, and interlisp. Flash provides record level access to a file with multiple indexes using symbolic keys. It is portable and written in Pascal with support routines in dec System 20 macro. The file access system is designed to run on computers of various sizes and capabilities, including micros. Concurrent and simultaneous access by several users is supported given that the operating systems provides multiprogramming. Flash is designed to be highly reliable. It assumes the existence of underlying operating system file services that read or write named files directly. Transfer to files occurs in units which are efficient, typically a block.