This paper addresses the question of how information-theoretically-derived compact representations can be applied in practice to improve storage and processing efficiency in DBMS. Compact data representation has the potential for savings in storage, access and processing costs throughout the systems architecture and may alter the balance of usage between disk and solid state storage. To realise the potential performance benefits, however, novel systems engineering must be adopted to ensure that compression/decompression overheads are limited. This paper describes a basic approach to storage and processing of relations in a highly compressed form. A vertical columnwise representation is adopted in which columns can dynamically vary incrementally in both length and width. To achieve good performance query processing is carried out directly on the compressed relational representation (using a compressed representation of the query), thus avoiding decompression overheads. Measurements of performance of the Hi-base prototype implementation are compared with those obtained from conventional DBMS.

Future database applications will require significant improvements in performance beyond the capabilities of conventional disk based systems. This paper describes a new approach to database systems architecture, which is intended to take advantage of solid-state memory in combination with data compression to provide substantial performance improvements. The compressed data representation is tailored to the data manipulation operations requirements. The architecture has been implemented and measurements of performance are compared to those obtained using other high-performance database systems. The results indicate from one to five orders of magnitude speed-up in retrieval, equivalent or slightly faster performance during insertion (and compression) of data, while achieving approximately one order of magnitude compression in data volume. The resultant architecture is thus capable of greater cost/effectiveness than conventional approaches.

The authors present a genetic approach for determining the priority order in the commitment of thermal units in power generation. The objective of the problem is to properly schedule the on/off states of all thermal units in a system to meet the load demand and the reverse requirement at each time interval, such that the overall system generation cost is a minimum, while satisfying various operational constraints. The authors examine the feasiblity of using genetic algorithms and report some simulation results in near-optimal commitment of thermal units in a power system.

Abstract Approximate string matching is an important operation in information systems because an input string is often an inexact match to the strings already stored. Commonly known accurate methods are computationally expensive as they compare the input string to every entry in the stored dictionary. This paper describes a two‐stage process. The first uses a very compact n‐gram table to preselect sets of roughly similar strings. The second stage compares these with the input string using an accurate method to give an accurately matched set of strings. A new similarity measure based on the Levenshtein metric is defined for this comparison. The resulting method is both computationally fast and storage‐efficient.

Conventional viewdata systems have two main drawbacks. First, they store information in a hierarchic structure which may be more naturally held as a network. As a result, a user may find himself forced to search through the structure in an illogical fashion. Further, the information provider, who is expected to supply not only the data but also its structure, is given very little aid. This paper describes the facilities of a modified viewdata system, Vulcan, which overcomes these problems, and its associated hierarchy specification language, VPREP. Information can be structured as a ‘natural’ network but is presented to the user as a logically consistent hierarchy. The VPREP language offers formal assistance for the specification, development and maintenance of the information network structure. The system described has been in use for several months.

Abstract This note describes a robust, simple‐to‐implement filestore. The filestore provides facilities for creating named, dynamically allocated files which can be accessed via a block level interface (both randomly and sequentially). The design is particularly well‐suited to the type of environment found on personal computers, word processors, and other stand alone systems where a high degree of resilience against hardware and software malfunction is required. It is ideally suited for use with floppy discs or any other cheap removable rotating medium, because of its high reliability and good performance, gained at the price of a slight reduction in available disc capacity.

Abstract Program development can be greatly speeded by a dump analysis program which makes the state of a program more visible to the programmer. A single comprehensive analysis presenting as much of the relevant material in as concise a manner as possible has proved superior in use to the alternative of interactive analysis one item‐at‐a‐time. The methods adopted in the STAB utility to achieve comprehensive and concise output are described. The system and compiler modifications necessary to support this type of system are discussed.