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Overlapping B+-trees: an Implementation of a Transaction Time Access Method
			   (the source code)
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			    October 8, 2000


Table of Contents
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 1. Overview
 2. Copyright and Distribution
 3. Documentation
 4. What to Read
 5. Bugs
 6. File List
 7. Acknowledgements



1. Overview
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Overlapping B+-trees is an efficient indexing method for transaction 
time databases. Modification operations (i.e. insertions, deletions 
and updates) are allowed at the current version, whereas queries 
are allowed to any temporal version, i.e. either in the current or 
in past versions. 
Using this structure, snapshot and range-timeslice queries can be answered,
optimally. However, the fundamental objective of the proposed method is 
to deliver efficient performance in case of a general pure-key query 
(i.e. ``history of a key").



2. Copyright and Distribution
-----------------------------
This source code was created by Mr. Theodoros Tzouramanis 
<theo@delab.csd.auth.gr>, from Aristotle University of Thessaloniki,
Department of Informatics, Thessaloniki, Greece,
under the supervision of Prof. Yannis Manolopoulos and 
Prof. Nikos Lorentzos.
Permission is granted to copy this software, to redistribute it
on a nonprofit basis, and to use it for any purpose, subject to
the following restrictions and understandings:
a. Any copy made of this software must include this copyright notice
   in full.
b. All materials developed as a consequence of the use of this
   software shall duly acknowledge such use, in accordance with the usual
   standards of acknowledging credit in academic research.
c. The authors have made no warranty or representation that the
   operation of this software will be error-free or suitable for any
   application, and they are under no obligation to provide any
   services, by way of maintenance, update, or otherwise.  The software
   is an experimental prototype offered on an as-is basis.
d. Redistribution for profit requires the express, written permission
   of the authors.



3. Documentation
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The source code was written in C programming language
(for Borland C++, Ver. 3.1, by Borland International, Inc.).
We provide brief explanations for every routine in the 
course code (in English).

Precondition: the program has to be run in a directory where the datafile 
              "input.dat" is. Otherwise: an error message is printed.

After running the program, when you look in your directory you will find 
the following new files:
* experime.txt: Its a log file to printed out the values of some 
                parameter numbers that describe the performance of the 
                Overlapping B+-trees.
* rec.dat     : Contains the T-trees.
* trans.dat   : Contains the Transaction Time Tree (TTT structure).



4. What to Read
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Before trying to understand the source code, please read carefully 
the following papers:

[TML98] T. Tzouramanis, Y. Manolopoulos and N. Lorentzos: ``Overlapping
        B+-Trees : An Implementation of a Transaction Time Access Method'',
        Data and Knowledge Engineering, Vol.29, No.3, pp.381-404, 1999.
[LD86]  S.D. Lang and J.R. Driscoll: Improving the Differential File 
        Technique via Batch Operations for Tree Structured File 
        Organizations, Proceedings of the IEEE International Conference 
        on Data Engineering, Los Angeles, CA, 1986.



5. Bugs
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Send bug reports to Theodoros Tzouramanis <theo@delab.csd.auth.gr>.
When reporting bugs, please include the exact wording of any error messages.
Don't expect a fast response - the work I'm doing now takes priority.



6. File List
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This zip file must contain the following files:

  OVERBT.H
  OVERBT.C
  README.TXT	    (this file)
  INPUT.DAT         (input datafile)



7. Acknowledgements
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Mr. Apostolos Papadopoulos for his helpful comments.

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