A Framework for Logical-Level Changes Within Database Systems

Sockut,

doi:10.1109/mc.1985.1662890

Cited by 9 publications

(3 citation statements)

References 30 publications

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“…Logical redefinition may, of course, affect not just data instances (i.e., in persistent storage), but also the physical definition, view definitions, objects' methods, and application programs [Sockut 1985]. However, strategies that we describe below can reduce the impact.…”

Section: Strategies For Online Logical Redefinitionmentioning

confidence: 99%

Online reorganization of databases

Sockut

Iyer

2009

ACM Comput. Surv.

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In practice, any database management system sometimes needs reorganization, that is, a change in some aspect of the logical and/or physical arrangement of a database. In traditional practice, many types of reorganization have required denying access to a database (taking the database offline) during reorganization. Taking a database offline can be unacceptable for a highly available (24-hour) database, for example, a database serving electronic commerce or armed forces, or for a very large database. A solution is to reorganize online (concurrently with usage of the database, incrementally during users' activities, or interpretively). This article is a tutorial and survey on requirements, issues, and strategies for online reorganization. It analyzes the issues and then presents the strategies, which use the issues. The issues, most of which involve design trade-offs, include use of partitions, the locus of control for the process that reorganizes (a background process or users' activities), reorganization by copying to newly allocated storage (as opposed to reorganizing in place), use of differential files, references to data that has moved, performance, and activation of reorganization. The article surveys online strategies in three categories of reorganization. The first category, maintenance, involves restoring the physical arrangement of data instances without changing the database definition. This category includes restoration of clustering, reorganization of an index, rebalancing of parallel or distributed data, garbage collection for persistent storage, and cleaning (reclamation of space) in a logstructured file system. The second category involves changing the physical database definition; topics include construction of indexes, conversion between B + -trees and linear hash files, and redefinition (e.g., splitting) of partitions. The third category involves changing the logical database definition. Some examples are changing a column's data type, changing the inheritance hierarchy of object classes, and changing a relationship from one-to-many to many-to-many. The survey encompasses both research and commercial implementations, and this article points out several open research topics. As highly available or very large databases continue to become more common and more important in the world economy, the importance of online reorganization is likely to continue growing.

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Section: Strategies For Online Logical Redefinitionmentioning

confidence: 99%

Online reorganization of databases

Sockut

Iyer

2009

ACM Comput. Surv.

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“…Note that its fields include the unique iilcntificr fur hotels (HNAME), the iiiii(|uc identifier for conventions (UNAME, CYEAR), and the intersection data (HQ, RMSTAKEN). I'lirther information about the logical level of database conversion can be found in [20], [21], and [24].…”

Section: Logical Conversion From Navigational To Relational Structuresmentioning

confidence: 99%

Physical design equivalencies in database conversion

Gillenson

1990

Commun. ACM

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“…An example of structural reorganization is schema reorganization in databases [Sockut 1985]. Going to the right in this dimension indicates stronger support of identity.…”

Section: Degrees Of Support Of Identitymentioning

confidence: 99%

Object identity

Khoshafian¹,

Copeland²

1986

Conference Proceedings on Object-Oriented Programming Systems, Languages and Applications - OOPLSA '86

231

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Identity is that property of an object which distinguishes each object from all others. Identity has been investigated almost independently in general-purpose programming languages and database languages. Its importance is growing as these two environments evolve and merge.We describe a continuum between weak and strong support of identity, and argue for the incorporation of the strong notion of identity at the conceptual level in languages for general purpose programming, database systems and their hybrids. We define a data model that can directly describe complex objects, and show that identity can easily be incorporated in it.Finally, we compare d~erent implementation schemes for identity and argue that a surrogate-based implementation scheme is needed to support the strong notion of identity.

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A Framework for Logical-Level Changes Within Database Systems

Cited by 9 publications

References 30 publications

Online reorganization of databases

Online reorganization of databases

Physical design equivalencies in database conversion

Object identity

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