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Re: MYDUL avaialbe for recovery, another choise of DUL.

From: Jonathan Lewis <>
Date: Tue, 27 Sep 2005 06:17:00 +0000 (UTC)
Message-ID: <dhao4s$1ok$>

<> wrote in message
> AnySQL (d.c.b.a) wrote:
>> Why I want to reverse DUL, I just wrote one of mine according to my
>> knowledge of oracle block format. Spent a lot of time on it, illegal?
> Most certainly it is, as stated in the Oracle licence agreement:
> "(d) prohibits causing or permitting the reverse
> engineering, disassembly or decompilation of the Program(s); ..."
> You have, in your infinite wisdom, reverse-engineered DUL. You have,
> therefore, violated the terms of the Oracle licencing agreement and, as
> such, are subject to prosecution.
> Have a nice day.
> David Fitzjarrell

That introduces an interesting point for many of the Oracle 'gurus'. When Steve Adams writes something about how the redo writer works and how to set the best size for the log buffer and files, has he "caused or permitted the reverse engineering" of part of the code.

When I describe how the hash join mechanism works, or how the cost based optimiser does its arithmetic have I done the same.

When Cary Millsap explains what's in a trace file, and where tkprof gets it wrong, has he done the same.

Where can you draw the line ?

If someone gives you a raw datablock and says:

    The information on this block is from a     table with N columns of types x,y, and z you might be able to write a program to decode the dump without knowing the block came from an Oracle database.

If you then claimed you could dump the block with a self-consistent image of all committed changes as at a particular SCN, then I think you would be on very shaky ground, because you would have had to apply very detailed knowledge of the operation of the software that produced, and reads, the block.

This is all just conjecture, by the way, but I can't help thinking that the people who explain Oracle internals (correctly) might technically be in breach of their licence agreements.


Jonathan Lewis
Cost Based Oracle - Volume 1: Fundamentals
On-shelf date: Nov 2005
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Received on Tue Sep 27 2005 - 01:17:00 CDT

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