Re: Help: Rollbacks Keep Blowing Up-v7.1.4

In article: <outputD482pu.A7B_at_netcom.com> output_at_netcom.com (Output Services) writes:
>
> In article <3h7amc$s7q_at_newsbf02.news.aol.com> lgaard_at_aol.com (LGAARD) writes:
> >On 2 Feb 1995, Bill Hungerford wrote:
> >
> >> Multiple SQL scripts running on system are blowing up due to rollback
> >> segments ("snapshot too old").
> >>
> >> Also, it appears that when these jobs run, the rollback segments aren't
> >> going into extents.
> >>
> >
> >To review: more extents at optimal (not to more than 30 probably) and/or
> >more rollback segments.
> >I hope that helps.
> >Laurel
>
> I have very littly knowledge on this, but... I have had problems with
> RB segments NOT extending when there was plenty of space left in the
> tablespace and the segment needed to extend. I also got a snapshot
> too old message, and we never run more than three simultaneous trans.
>
> I think the segment can only extend under certain circumstances,
> and if those are not met, it will blow up.
>
> I got sick of busting them, so I created 8 equal rollback segs, each with
> min 16 extents, and each extent 16 meg. Problem solved.
>
> Hope this helps,
> Marty
> --
> output_at_netcom.com
>
>

-- 

	Hi there !

	Rollback segments will extend when rquired, up to a maximum
which is dependant on the size of the db_block_size init.ora parameter.

	When an object is created in the database the initial 
extent is allocated to the object. The first block is then used 
to hold pointers to the other extents, when they are created.

	If you have a 2k db_block_size then the maximum number of
pointers that can be created is 121. Thus you can only have 121 extents.



---
	Tim London			phone :	+44 753 662393
	Oracle DBA,Trainer and		mobile:	+44 836 287064
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