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An Incomplete Data Cube - A Perl Implementation
A Data Cube Tool for Missing Data
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Curtis Dyreson
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0.90 - December 7, 1997
POD Documenation - on-line documentation for every package
IncompleteDataCube.tar.gz - tarred, gzipped Perl 5 modules

How to use the cube

There are three phases to using an incomplete data cube. The code that you download is already configured to build an example cube (the README file in the release package will provide more details).
  1. The dimensions of the cube must be constructed. A dimension consists of units and measures. The data cube implementor (DCI) writes one text file to describe each dimension. These specifications are then parsed and (internally) stored as graphs and tables of names within the cube store.
  2. The DCI edits a list of cubette specifications. These specifications are then parsed and (internally) stored within the cube store. During the parsing, flex (flex is a lexical analyser generator) source is produced to sieve data from a text file and populate the incomplete data cube. The flex source is compiled and input data is passed through the resulting lexical analyser to populate the cube. (Only flex was up to the task of handling the hundreds of thousands of regular expressions that are potentially produced during construction of the data sieve. It is unfortunate because this introduces a non-Java and non-Perl dependency, hence the code for the sieve is not 100% pure Java or Perl).
  3. Queries can now be made on the populated cube either through a GUI or by calling the appropriate methods directly.
Currently, the incomplete data cube is designed to obtain data from a text file, the example cube parses an HTTPD access log. Specifications for units and measures in three dimension (Time, Machines, and Pages) are also provided.

Below we outline the current state of the implementation. While the cube is currently functional, much remains to be done.


  • Perl 5 - the code is Object-oriented
  • dbm - Unix dbm files are used to store the cube
  • flex (a lexical analyzer generator) - to sieve data, not for the cube per se
  • development environment is UNIX (SunOS5) - untested in other environments (but, it's Perl so there should few portability issues!)

Implemented Features

  • unlimited number of dimensions
  • unlimited number of measures (e.g., days, years, countries)
  • unlimited number of units (e.g., '1 October 1997', 1995, Australia)
  • any user-specified measures and units (none are "built-in")
  • input data parsed from a text file
  • data is "filtered" through cubette specifications
  • data cube data, units, and measures stored in generic database, for speed the database is currently configured to Unix dbm files
  • query satisfaction algorithm
  • sum queries
  • CGI-bin GUI for query engine
  • sparse storage of data, only points in the cube that have data are materialized

Unimplemented features (wish list)

  • incomplete data cube store configured to use Perl DB API
  • input data to be retrieved from database using Perl DB API
  • GUI to modify cubette store
  • deletion/renaming of units/measures
  • min - max queries
  • upper - lower bounds on query results
  • completeness measures for query results
  • suggestion of alternate answers

Curtis E. Dyreson © 1995-2001. All rights reserved.
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