Algorithms and Data Structures
Volume 519 of the series Lecture Notes in Computer Science pp 141152
A lineartime scheme for version reconstruction
 Lin YuAffiliated withDepartment of Computer Science, State University of New York at Albany
 , Daniel J. RosenkrantzAffiliated withDepartment of Computer Science, State University of New York at Albany
Abstract
An efficient scheme to store and reconstruct versions of sequential files is presented. The reconstruction scheme involves building a data structure representing a complete version, and then successively modifying this data structure by applying a sequence of specially formatted differential files to it. Each application of a differential file produces a representation of an intermediate version, with the final data structure representing the requested version.
The scheme uses a linked list to represent an intermediate version, instead of a sequential array, as is used traditionally. A new format for differential files specifying changes to this linked list data structure is presented. Algorithms are presented for using such a new format differential file to transform the representation of a version, and for reconstructing a requested version. Algorithms are also presented for generating the new format differential files, both for the case of a forward differential specifying how to transform the representation of an old version to the representation of a new version, and for the case of a reverse differential specifying how to transform the representation of a new version to the representation of an old version.
This new version reconstruction scheme takes time linear in the sum of the size of the initial complete version and the sizes of the file differences involved in reconstructing the requested version. In contrast, the classical scheme for reconstructing versions takes quadratic time. The time cost of the new differential file generation scheme is comparable to the time cost of the classical differential file generation scheme.
 Title
 A lineartime scheme for version reconstruction
 Book Title
 Algorithms and Data Structures
 Book Subtitle
 2nd Workshop, WADS '91 Ottawa, Canada, August 14–16, 1991 Proceedings
 Pages
 pp 141152
 Copyright
 1991
 DOI
 10.1007/BFb0028257
 Print ISBN
 9783540543435
 Online ISBN
 9783540475668
 Series Title
 Lecture Notes in Computer Science
 Series Volume
 519
 Series ISSN
 03029743
 Publisher
 Springer Berlin Heidelberg
 Copyright Holder
 SpringerVerlag
 Additional Links
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 Industry Sectors
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 Editors
 Authors

 Lin Yu ^{(1)}
 Daniel J. Rosenkrantz ^{(1)}
 Author Affiliations

 1. Department of Computer Science, State University of New York at Albany, 12222, Albany, NY
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