Anil Nori

The implementation of an integrated concurrency control and recovery scheme

This paper describes the implementation level design of an integrated concurrency control and recovery scheme based on the maintenance of multiple versions of data objects in a database. The concurrency control mechanism enhances parallelism by eliminating interference between retrieval and update transactions. The recovery mechanism permits efficient transaction and system recovery by keeping before-images of data objects at the page (block) level. This paper addresses the key technical problems in the implementation of such an integrated scheme. We present an efficient garbage collection algorithm for reclaiming storage space used by old versions of data objects that will no longer be accessed. We also propose an on-line backup algorithm that will permit the backup procedure to run in parallel with regular transactions. This integrated concurrency control and recovery scheme is being implemented in the LDM: the local database manager component of a distributed database management system, now being developed by Computer Corporation of America, that will support the ADAPLEX database application programming language [Chan81a, Smith81].

Bringing objects to the mainstream

Oracle provides an open type system that is consistent with ANSI SQL3 and provides interoperability of SQL with C/C++, Java and CORBA data models. By providing native support for objects in the database and navigational access to database objects from different host languages, we are reducing the impedance mismatch between the applications and the database. The Oracle server also provides a database extensibility framework that allows a tight integration of domain-specific data and logic with the database server. This database extensibility is achieved in an open, safe and manageable fashion in a network-centric computing architecture.

Storage and access structures to support a semantic data model

ABSTRACT This paper describes the design of storage and access structures for a high performance Ada * compatible database management system. This system supports the database application programming language ADAPLEX [Smith81, Smitb82], which is the result of embedding the database sublanguage DAPLEX [Shipman81] in the general purpose language Ada [DoD80]. A prominent feature of the underlying data model is its support for generalization hierarchies [Smith77] which are intended to simplify the mapping from conceptual entities to database objects. An in-depth discussion of the rationale behind our choice of storage and access structures to support semantics intrinsic to the data model and to permit physical database organization tuning is provided in this paper.

Bringing object-relational technology to the mainstream

Over the last few years, Oracle has evolved its flagship relational database system into an Object-Relational system by adding an extensible type system, object storage, an object cache, an extensible query and indexing framework, support for multimedia datatypes, a server-based scalable Java virtual machine, as well as enhancing its SQL DDL and DML language. These extensions were done with the practical goal of bringing objects to mainstream use.

Object-relational database systems (tutorial): principles, products and challenges

Object-relational database systems, a.k.a. “universal servers,” are emerging as the next major generation of commercial database system technology. Products from relational DBMS vendors including IBM, Informix, Oracle, UniSQL, and others, include object-relational features today, and all of the major vendors appear to be on course to delivering full object-relational support in their products over the next few years. In addition, the SQL3 standard is rapidly solidifying in this area. The goal of this tutorial is to explain what the key features are of object-relational database systems, review what todays products provide, and then look ahead to where these systems are heading. The presentation will be aimed at general SIGMOD audience, and should therefore be appropriate for users, practitioners, and/or researchers who want to learn about object-relational database systems.

A tool kit for database programming in Ada

This paper describes an Ada-compatible database application development environment being designed and prototyped at Computer Corporation of America. This environment is intended to provide uniform access to centralized, homogeneously distributed, and heterogeneously distributed databases. There are two key interfaces: an interactive interface called Daplex which is based on a semantically rich data model and a powerful access language, and an application program interface called Adaplex which consists of an expression level integration of Daplex with Ada. The objective of this paper is to explain our rationale for designing Adaplex and to describe its support environment.

A database management capability for Ada

The data requirements of mission critical defense systems have been increasing dramatically. Command and control, intelligence, logistics, and even weapons systems are being required to integrate, process, and share ever increasing volumes of information. To meet this need, systems are now being specified that incorporate data base management subsystems for handling storage and retrieval of information. It is expected that a large number of the next generation of mission critical systems will contain embedded data base management systems. Since the use of Ada has been mandated for most of these systems, it is important to address the issues of providing data base management capabilities that can be closely coupled with Ada. A comprehensive distributed data base management project has been investigated. The key deliverables of this project are three closely related prototype systems implemented in Ada. These three systems are discussed.