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Home -> Community -> Usenet -> c.d.o.server -> Re: MYDUL avaialbe for recovery, another choise of DUL.
Comments embedded.
jkstill_at_gmail.com wrote:
> Jonathan Lewis wrote:
> > <fitzjarrell_at_cox.net> wrote in message
> > news:1127793538.884457.114420_at_g43g2000cwa.googlegroups.com...
> > >
> > > 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.
> >
> >
> >
> > --
> > Regards
> >
> > Jonathan Lewis
> >
> > http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html
> > Cost Based Oracle - Volume 1: Fundamentals
> > On-shelf date: Nov 2005
> >
> > http://www.jlcomp.demon.co.uk/faq/ind_faq.html
> > The Co-operative Oracle Users' FAQ
> >
> > http://www.jlcomp.demon.co.uk/appearances.html
> > Public Appearances - schedule updated 4th Sept 2005
>
>
>
>
>
Such traces are provided by Oracle without the use or construction of third-party tools. As you've stated the explanation of the trace symbols is provided by Oracle Corporation; Oracle provides these traces to enable a DBA to properly tune queries and the database. This, in my mind, is a far different situation than knowingly writing a replacement, albeit incomplete, of DUL.
> I don't know if reverse engineering a data format (such as in
> myDUL) is equivalent to reverse engineering software.
>
And you may be correct, however I wouldn't want to be on the receiving end of any communication from the legal department of Oracle Corporation. DUL is a proprietary software tool used, in the most extreme cases, to attempt data recovery from corrupted datafiles. This tool is also accompanied by a trained technician who can properly operate it. If such a tool requires specially educated personnel I certainly wouldn't trust any DBA to use it, much less trust a second-rate copy in anyones hands.
> Many utilities exist that can read MS Office formats, some of
> them are open source - this seems analagous to me.
Reading the contents of a Word document is far different, to me, than reading the contents of a corrupted, proprietary-format datafile, especially with a tool that is incomplete, as admitted by the programmer. Lacking the ability to recover LOB data, comporessed indexes and IOTs certainly leads me to wonder why I should trust such a tool to correctly read any other data in a corrupted file. The OP has claimed his tool is "ready for recovery", yet misses some data structures, meaning tables with LOB columns will be incomplete upon 'recovery', IOTs will be missing as well as compressed indexes. To me this is a failed attempt at reverse-engineering DUL; it is also an accident waiting to happen. Using this 'tool' to 'recover' corrupted datafiles would violate any service agreements between Oracle and the party using said 'tool' as it is NOT Oracle's DUL utility. There is nothing good about this work as I see the situation. Possibly I am wrong about the legality of this software and the process used to create it; from what I have read thus far I do not believe I am. That notwithstanding, this 'tool' is a hazard for anyone to use, whether it be legal or not. I certainly wouldn't trust it to recover my data.
>
I wholeheartedly agree.
> Jared
David Fitzjarrell Received on Tue Sep 27 2005 - 20:36:05 CDT
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