Re: Rollback Segments

You are right. The solution is not the increate the next extent or the max extent of the rollback segment but to add more rollback segments to the system.

WInnie

Me_at_this.com wrote in message <35d87a3e.26326095_at_newshost.us.oracle.com>...
>Jerry and Carlos,
>
> Assigning the large rollback segment to Carlos' long running
>transaction will not help. He needs to add more rollback segments.
>The ora-1555 tells you that during your long running transaction,
>somebody modified a block and committed a change to the block during
>the time your transaction has been running. Then, another transaction
>overlaid the old version of the block in the rollback segment. Your
>transaction tries to get its read consistent view and it's not there
>anymore.
>
> Since RBS's are used in round robin fashion, by adding more
>RBS's, it will take longer for your system to roll around to re-using
>an RBS, overlaying the version of the block you want. If you can't
>add more rollback segments, the only other alternative is running the
>app at truly off-peak time, like when NOBODY else is on the system.
>ORA-1555's are a result of Oracle's implementation of read-consistency
>and except for solution 2 (NOBODY), there is no guarantee you will not
>see an ora-1555.
>
>HTH,
>
>Frank
>
>
>
>
>On Mon, 17 Aug 1998 13:41:45 -0400, Jerry Gitomer
><jgitomer_at_ictgroup.com> wrote:
>
>>Hi Carlos,
>>
>> Adding more rollback segments won't help. There are three alternatives
>>(one of which may not apply in your case):
>>
>> 1. Increase maxextents (I think you are at the limit for NT)
>>
>> 2. Increase initial and/or next extents from 50K to at least 100K.
>>
>> 3. Create a very large rollback segment and then assign the big
>>transaction to it using the SET TRANSACTION command.
>>
>> My personal preference is the third alternative since, in most cases,
>>only one very large rollback segment is needed and it is, IMHO, more
>>desirable to have less disk space tied up.
>>
>>regards
>>
>>Jerry
>>
>>
>>
>>
>>
>>calberto_at_my-dejanews.com wrote:
>>>
>>> Hi all!
>>>
>>> I'm having problems with rollback segments in Oracle. We, in our
company, have
>>> an long-running application (about 3 hours) which after 2 hours give us
the
>>> following message :
>>>
>>> ORA 01555 - Snapshot too old .....
>>>
>>> The server currently has 16 rollback segments, which one with the
following
>>> parameters :
>>>
>>> INITIAL - 50K
>>> NEXT - 50K
>>> OPTIMAL - DEFAULT (I suppose Oracle's default is NULL)
>>> MINEXTENTS - 2
>>> MAXEXTENTS - 121
>>>
>>> Is the solution increase the NEXT parameter?
>>>
>>> Beyond this, I have some doubts :
>>>
>>> 1) I have manually put all these segments online, but when the machine
>>> rebooted (for other reasons), Oracle have put some of them offline. Why?
>>>
>>> 2) Since my OPTIMAL parameter is the default, when Oracle will release
the
>>> extents of the segments?
>>>
>>> 3) All these rollback segments are in one tablespace which has 2
datafiles of
>>> 20 MB each, but there is only 2 MB free. Is this related with the
problem?
>>>
>>> We have Oracle 7.3 running on NT 4.0.
>>>
>>> Thank in advanced,
>>>
>>> Carlos
>>>
>>> -----== Posted via Deja News, The Leader in Internet Discussion ==-----
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>>
>>--
>>Jerry Gitomer ICT Group
>>jgitomer_at_ictgroup.com Langhorne PA
>>jgitomer_at_yahoo.com Opinions are mine not those of ICT Group
>
Received on Mon Aug 17 1998 - 22:21:55 CDT