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

From: Joel Garry <>
Date: 27 Sep 2005 14:56:27 -0700
Message-ID: <>

Jonathan Lewis wrote:
> <> 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); ..."

Violation of a contract term isn't necessarily illegal, it just exposes you to lawsuits for a remedy. I wouldn't want to be in China when Oracle convinces them to crack down...

> >
> > 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.

Putting it that way makes it sound criminal, which it usually isn't, although you can technically say a civil case is being prosecuted.

> >
> > 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 ?

Very simply, the line has been drawn by various governments to make it technically illegal to do common software engineering tasks. In addition, lawyers for all large software vendors have done the same thing contractually for jurisdictions where they can.

> 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.

There is simply no legal way to do it, certainly under US law. I am not a lawyer, so take any legal opinion I may give with much seasoning. - even the "strings" command is reverse engineering. DMCA criminalizes the copyright issues. It would be ironic if people who explain things incorrectly would be on more solid legal ground, but reverse engineering doesn't have to be correct, just attempted.

Should we worry about getting slammed by Oracle? Most of us, not generally. Guru's noted above might want to check with actual lawyers (and let us know what they say). I don't think Oracle would actually go after anyone like them (except Oracle employees in some situations, maybe), but lawyers are paid to anticipate and defend against the worst case.

I believe Oracle _should_ give access to the details at all levels through documentation (and included instrumentation), but I don't think that is going to happen, since the withholding of information is valuable to the corporation. I think the current situation in general sucks, and we haven't seen yet how badly it can suck.

I am salivating in anticipation of your book, Jonathan! Please don't let any of this legal mumbo-jumbo get in the way.


-- is bogus.
RIP Donald James Yarmy 1923-2005 AKA Don Adams AKA Maxwell Smart.
"Sorry about that Chief..."
Received on Tue Sep 27 2005 - 16:56:27 CDT

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