Re: Migrating from MS Sql Server to Oracle

If you have terabytes it is a bad generalization. But if you have terabytes in SQL Server it strains credibility. I've consulted at AT&T within the last year and all databases that large of which I am aware were either in Oracle or Teradata.

Either way ... you have a project that will take months ... not weeks. And AT&T is a sophisticated enough company to know that.

Daniel Morgan

luc wrote:

> To add: there are several terrabyte databases in SQL Server. It may be that
> a typical sql server
> database has less than that but how big is a typical Oracle database? So I
> think this is
> a bad generalization.
>
> "BP Margolin" <bpmargo_at_attglobal.net> wrote in message
> news:3c97a68a_3_at_news1.prserv.net...
> > Daniel,
> >
> > In general, excellent advice ... I have only two issues with your
> comments:
> >
> > "> But since it is SQL Server likely you are talking less than 10
> > > million rows ... "
> >
> > There are many SQL Server applications that have 1 or even 2 orders of
> > magnitude more data.
> >
> > > PS: In the Oracle world ... we test stuff before we throw it over the
> > > cubicle wall.
> >
> > Might be true of applications written by Oracle developers outside of
> > Oracle, but the number of bugs contained in the applications written by
> > Oracle employees in their commercial products seems to be at least on a
> par,
> > if not worse, than by Microsoft employees.
> >
> > Otherwise, as I said, I think you have provided Mark with very sound
> advice.
> >
> > -------------------------------------------
> > BP Margolin
> > Please reply only to the newsgroups.
> > When posting, inclusion of SQL (CREATE TABLE ..., INSERT ..., etc.) which
> > can be cut and pasted into Query Analyzer is appreciated.
> >
> > "damorgan" <damorgan_at_exesolutions.com> wrote in message
> > news:3C976E36.EFB49F51_at_exesolutions.com...
> > > I would say that it is technically possible to move the tables in an
> hour.
> > > Just reverse engineer them with a tool such as ERwin and then rebuild
> from
> > > generated DDL. Moving the data is impossible to estimate as you gave no
> > > volumes. But since it is SQL Server likely you are talking less than 10
> > > million rows so likely a day including writing the SQL*Loader control
> > > files.
> > >
> > > But when it comes to the code ... you are not talking about migration.
> You
> > > are talking about a complete and total rewrite. Unless, of course, you
> > > have some over-riding urge for bad performance, corrupt data, and
> unhappy
> > > management and customers.
> > >
> > > Oracle is not just SQL Server with the profits going to some guy named
> > > Larry instead of some guy named Bill. It has an entirely different model
> > > that involves multiversioning ... something that doesn't exist in SQL
> > > Server. The transaction model is different, the locking model is
> > > different, the resource issues are different, etc.
> > >
> > > You should start buy purchasing a copy of Tom Kyte's book "expert
> > > one-on-one Oracle" and reading the first three chapters. Then, and only
> > > then, make an estimate. You don't say how many stored procedures, or
> what
> > > they do, or how complex, but my totally blind guess is that unless you
> > > want to be responsible for a mess ... you are talking about months.
> > >
> > > PS: In the Oracle world ... we test stuff before we throw it over the
> > > cubicle wall. So figure in time for writing unit test scripts and
> actually
> > > using them.
> > >
> > > And a word of warning about migration tools. From what I've seen they
> > > produce remarkably bad code often not understanding the differences
> > > between static cursors and ref cursors and other important issues.
> > >
> > > Good luck.
> > >
> > > Daniel Morgan
> > >
> > >
> > >
> > >
> > > Mark Kessler wrote:
> > >
> > > > Hello all,
> > > > I am facing the problem of migrating quite a big database (+100 tables
> > > > and stored procedures) from an MS Sql Server to an Oracle 8i Server.
> > > >
> > > > No I am trying to get an estimation of the necessary effort to put
> > > > into this.
> > > >
> > > > Assuming the following situation: Being neither an expert in Ms Sql or
> > > > Oracle but more an advanced user, and only starting to get inside into
> > > > the database I have to migrate..
> > > >
> > > > Would you say that it this possible to accomplish the migration in a
> > > > matter of days or weeks, when using a migration tool like the Oracle
> > > > Migration workbench? Or do I have to expect to put hand on every
> > > > stored procedure manually?
> > > >
> > > > I would appreciate any input very much.
> > > >
> > > > Mark Kessler
> > >
> >
> >
Received on Thu Mar 21 2002 - 10:10:09 CST