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Swendel wrote:
> All of you, thank you very much for your contributions.
> I installed Oracle Migration Workbench (Oracle 9 version) and migrated a SQL
> Server 2000 database to Oracle 8.1.7.
> I realize and already expected to have to do some extra work to tailor the
> code for Oracle, but for my application this tool worked well enough as a
> start.
>
> Thanks again, cheers, Sander Wendel.
>
> "Ben Brugman" <benbrugman_at_onbekend.nl> wrote in message
> news:3d99c4ef.16147609_at_news.nl.uu.net...
> > On Sun, 29 Sep 2002 22:12:42 +0100, "Paul Brewer"
> > <paul_at_paul.brewers.org.uk> wrote:
> >
> > Oracle Workbench can convert some things for you,
> >
> > Reasonable:
> > Table's
> > Constraints
> > Indexes
> > (Remark clustered indexes are sometimes converted to PK, this
> > is not always correct).
> >
> > Tricky
> > Views
> > (Simple views get converted correctly, more complex views get
> > converted with a warning (there you should check the results).
> > Some views can not be converted. Most problematic are
> > outer joins and were constants are used in a join class).
> >
> > Not ?
> > I do not thing Stored procedures can be converted at all.
> > But there might be a way I do not know off.
> >
> > General problems.
> > Oracle uses case significant 30 character identifiers limiting the
> > the characterset to less characters than SQL-server.
> > Oracle uses a different join strategie. Although from Oracle 9,
> > it could be that the syntax is more similar.
> >
> >
> > Interfacing from application or application layers.
> > A lot of SQL can be the same in Oracle and SQL-server.
> > In most SQL-servers mixed mode with case not significant is
> > used, here everything should be turned to UPPERCASE.
> > (That is metadata, not the data).
> > For data most SQL-servers work also case not significant,
> > here this could lead to different results specifically in the
> > WHERE clause.
> >
> > Concurrency,
> > SQL-server uses locking and isolation levels.
> > Oracle uses snapshot isolation.
> > If READ-consistency was used in SQL-server then this should
> > be sufficient in Oracle. Most repeatable read functionality can
> > be reached by the Snapshot isolation. (Not completely sure there).
> > If in SQL-server the SERIALIZABLE level was used, one has to check
> > the application. If it depends on that the read data can not be
> > changed, then you have to alter the application, because Oracle
> > does not lock on reads. (And does not support Serializable completely)
> >
> > Performance.
> > Both Oracle and SQL-server have their strenghts and their weaknesses.
> > Primairy aim should be to get the application working correctly and
> > knowing for sure it works correctly. Specific attention should go to
> > concurrency even with testing software often concurrency issues do
> > not appear until the software is used a lot on a large scale.
> >
> > Depending on what features were used from one RDBMS the conversion
> > can be from quite simple to a complete redesign.
> >
> > ben brugman
> >
> >
> > >"Daniel Morgan" <dmorgan_at_exesolutions.com> wrote in message
> > >news:3D938351.E4630428_at_exesolutions.com...
> > >> Christoph Seidel wrote:
> > >>
> > >> > yes, this is the name :-)
> > >> >
> > >> > "Jim Kennedy" <kennedy-family_at_attbi.com> wrote in message
> > >> > news:YUEk9.451742$_91.643468_at_rwcrnsc51.ops.asp.att.net...
> > >> > > I think you mean the migration work bench. You can download it
> from
> > >> > > otn.oracle.com
> > >>
> > >> That being said the migration workbench is just the very first step in
> a
> > >> process that will require you to modify your code. There is no other
> way
> > >> unless data corruption, poor performance, a lack of scalability, and
> > >> minimal security are acceptable.
> > >>
> > >> The architecture differences between Oracle and SQL Server are vast.
> While
> > >> the code produced by Migration Workbench is compilable code. It is only
> a
> > >> starting point.
> > >>
> > >> Among the critical differences are things in the Oracle word referred
> to
> > >> by the following phrases:
> > >>
> > >> 1. Multiversioning
> > >> 2. Readers don't block writers
> > >> 3. Writers don't block readers
> > >> 4. Unlimited locks
> > >> 5. Bind variables
> > >>
> > >> If you don't understand these concepts and modify your code accordingly
> it
> > >> will suffer greatly. I would suggest to you a small investment in Tom
> > >> Kyte's book "Expert one-on-one Oracle" and especially the first three
> > >> chapters.
> > >>
> > >> Daniel Morgan
> > >>
> > >Agreed. If this is a serious project, I'd recommend re-engineering; not
> > >migration.
> > >
> > >Paul
> > >
> > >
> > >
> >
> > Ben Brugman
Before you begin modifying your code ... make sure you understand the huge architecture differences ... the basic one's which I can encapsulate in the following statements:
If you are not intimately familiar with these concepts and their implications get a copy of Tom Kyte's book "Expert one-on-one Oracle" and pay special attention to the first three chapters.
Daniel Morgan Received on Wed Oct 02 2002 - 10:01:41 CDT