Re: rbs' maxextents in LMT

Guang,

It can "eat up" only the segment it is assigned to, not the whole rbs tablespace, you will still have other segments.

Igor Neyman, OCP DBA
ineyman_at_perceptron.com

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Tuesday, January 07, 2003 2:08 PM

> Hi, Arup:
>
> I created lmt "rbs" this way:
>
> CREATE TABLESPACE RBS
> DATAFILE '/oracle/u02/oradata/YPD/rbs01.dbf' SIZE 2048M
> EXTENT MANAGEMENT LOCAL
> UNIFORM SIZE 2M;
>
> and then
>
> SQL> create rollback segment RBSTest1 storage(initial 2048K next 2048K)
> tablespace rbs;
>
> Rollback segment created.
>
> SQL> create rollback segment RBSTest2 storage(initial 2048K next 2048K
> MAXEXTENTS 300) tablespace rbs;
>
> Rollback segment created.
>
> SQL> select SEGMENT_NAME,INITIAL_EXTENT,NEXT_EXTENT,
> 2 MIN_EXTENTS,MAX_EXTENTS
> 3 from dba_rollback_segs
> 4 where SEGMENT_NAME like '%TEST%';
>
> SEGMENT_NAME INITIAL_EXTENT NEXT_EXTENT MIN_EXTENTS
> ------------------------------ -------------- ----------- -----------
> MAX_EXTENTS
> -----------
> RBSTEST1 4194304 2097152 1
> 32765
>
> RBSTEST2 4194304 2097152 1
> 32765
>
>
> It shows that you can not set MAXEXTENTS of a rollback segment when it is
> created in LMT. What I mean the "run away transaction" is a transaction
> that keep using rollback segment until it uses up all it's extents. In DMT
> case, we can set the MAXEXTENTS of all the rollback segments so that there
> is no transaction that can use the whole tablespace. But in LMT, it seems
a
> "run away" transaction can "eat up" the whole rbs tablespace because there
> is no MAXEXTENTS ( ie, MAXEXTENTS = unlimited). Does anyone know there is
> somewhere in Oracle Doc that I can find the answer of my question?
>
> Thanks.
>
> Guang
>
> ----------------
> Date: Mon, 06 Jan 2003 18:10:08 -0500
>
> Guang,
>
> You should use LMTs with UNFORM extent allocation of some size So create
the
> tablespaces and the rollback segments but not the INITIAL or NEXT.
>
> I am not sure what you meamn by runaway processes. If a transaction needs
> rollback segment space, it will need to extend it. You can still specify
> MAXEXTENTS to limit the number of extents.
>
> HTH
>
> Arup
>
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Igor Neyman
  INET: ineyman_at_perceptron.com

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