Re: rollback segment question

Hi Stef,

One thing to add.

With the way rollback (undo) is automatically handled in 9i (providing you don't get ORA600s), the sharing algorithm is improved in that RBS can "steal" extents from each other. This means the SET TRANSACTION statement is now redundant (and could cause errors unless appropriate parameters are set).

Cheers

Rihcard

Richard Foote wrote:
>
> Hi Stef,
>
> The short answer is no.
>
> The reason being that Oracle's way is better :)
>
> By allowing all rollback segments to be shared and used in a round robin
> fashion, this means all things being equal, that the load among the
> rollback segments be evenly spread. This is a desirable outcome.
>
> By "hard coding" which rollback segment belongs to which tablespace, or
> which table or which user, etc., you're increasing the likelihood of a
> particular RBS being overloaded while others are sitting back and
> relaxing.
>
> An option you do have if you really want to use a particular RBS at the
> transaction level, is to use the SET TRANSACTION USE ROLLBACK SEGMENT
> blah. This is typically done when the transaction is large and the blah
> RBS is a specially large sized one that can cope with the excess amount
> of data. This though is an exception and one that is quite commonly
> abused.
>
> Cheers
>
> Richard
>
> stef wrote:
> >
> > Hi, everybody
> >
> > I'm a newbie in Oracle :) and I would like to know one thing
> >
> > When you create a rollback segment, is it possible to "assign" the segment
> > to a specific
> > data tablespace..? like Sybase or sql server do.
> >
> > example:
> > In the same database "TEST_DB" :
> > 1) create a data tablespace "datas_01".
> > 2) create a second data tablespace "datas_02".
> > 3) then create a rbs called "global_rbs" (mapping on a tablespace YYYY, not
> > important )
> >
> > Now, as I can see, all datas_01 and datas_02 will "use" the same global_rbs
> > ok...
> > Can I say now, datas_01 use only global_rbs and datas_02 use... another rbs
> > for example ?
> >
> > thanx....