RE: A rollback segment question on minextents

While on the subject..
Please see the Oracle Metalink Note: 1029850.6. It says the first "block" of the first segment contains header information.

> -----Original Message-----
> From: Kumanan Balasundaram
> Sent: 15 March 2002 17:59
> To: 'ORACLE-L_at_fatcity.com'
> Cc: 'wisernet100_at_yahoo.com'
> Subject: RE: A rollback segment question on minextents
>
> Oracle recommends the size NEXT=INITIAL.
> So if I had 10M initial, then most of the initial beyond the
> header info will be wasted? Sure not!
>
> Kumanan
>
> -----Original Message-----
> From: Rachel Carmichael [SMTP:wisernet100_at_yahoo.com]
> Sent: 11 March 2002 21:48
> To: Multiple recipients of list ORACLE-L
> Subject: RE: A rollback segment question on minextents
>
> the first extent is used by oracle as the segment header to manage
> the
> transaction information within the rollback segment. The second
> extent
> contains the actual change vectors
>
>
> --- kumanan.balasundaram_at_qxl.com wrote:
> > Hi,
> >
> > My point was that it could allocate one more extent as per need.
> Why
> > the
> > need to minextents = 2?
> >
> > Thanks
> > Kumanan
> >
> > > -----Original Message-----
> > > From: Stephane Faroult [SMTP:sfaroult_at_oriole.com]
> > > Sent: 07 March 2002 20:54
> > > To: Multiple recipients of list ORACLE-L
> > > Subject: Re: A rollback segment question on minextents
> > >
> > > kumanan.balasundaram_at_qxl.com wrote:
> > > >
> > > > Hi,
> > > >
> > > > I was wondering why Oracle force minextents for rollback
> > > > segments to be two. Why can't we have minextents zero or
> > > > no minextents clause at all.
> > > >
> > > > We can surely set initial extent to be large enough ourselves
> > > > and next extent sized accordingly.
> > > >
> > > > Can someone enlighten me on the reason/thought behind this?
> > > >
> > > > Many thanks
> > > >
> > > > Kumanan Balasundaram
> > > > Database Administrator, IT
> > > > QXL ricardo plc
> > > > www.qxl.com
> > > > P: +44 (0)208 962 7409
> > >
> > > Oracle doesn't reuse an extent which contains active
> transactions.
> > What
> > > do you think would happen when you reach the end of your initial
> > extent
> > > ? Exactly.
> > > --
> > > Regards,
> > >
> > > Stephane Faroult
> > > Oriole Ltd
> > > --
> > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > --
> > > Author: Stephane Faroult
> > > INET: sfaroult_at_oriole.com
> > >
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> Please see the official ORACLE-L FAQ: http://www.orafaq.com
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> Author: Rachel Carmichael
> INET: wisernet100_at_yahoo.com
>
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Author: 
  INET: kumanan.balasundaram_at_qxl.com

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