CRC Compatible DF creator

Please Note:

The CRC compatible DF creator.

26th Mar 2001 - UPDATE: version 0.4 released

This program was inspired over dinner one night.  Grant Maizels and I were dragged out to a restaurant by our respective wives, who were both at my office as well.   Grants' wife (Tracey) was worried about an upgrade for a customer where there was no "clean" DB available, and the good old CRC problem was likely to appear.

Grant recalled discussion on the PEG by John Green et al, regarding the Schema Copy routine.  That got us to thinking about an alternative to Peter van Dam's crccopy program.  The problem here was direct manipulation of the meta schema.  This was not acceptable, and Grant even recalls a message from Gus saying so!  The alternative was obviously to create a DF that could be loaded, and gave the same CRCs.  Ah, but the biggest CRC problem still remaining - gaps in the _field-rpos.

To resolve this, we decided to create two DFs.  And so this program was born!   A very basic DF file describing the current DB is generated by our program, and loaded into a freshly created temp DB (using the Progress dictionary load routine of course! Thanks to Steve Brown).  Then, a delta DF is created between the two DBs (again using Progress dictionary routines) and applied to the temporary.  Finally, a CRC comparison is made between the two.  The two DFs can be used at any time, and if applied in the correct order, should always give the same CRCs as the original database.

This code tested on V8 Progress only.  In version 9 this process should be unneccesary, and currently doesn't work anyway due to dictionary program changes.

Please Read the following before Downloading this program

Copyright of the program:
This program is made available under the GNU GENERAL PUBLIC LICENSE Version 2, June 1991. Please see the file COPYING which should be located with the source code.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Kean Maizels and Grant Maizels
December 1999.

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Please Note:

The CRC compatible DF creator V0.4.

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Last updated 10th August 2005