Re: dropping Undo Tablespace

  • From: "Godwin vincent" <godwin.ror@xxxxxxxxx>
  • To: "Ted Coyle" <oracle-l@xxxxxxxxxxxx>
  • Date: Thu, 31 May 2007 16:10:04 -0400

    Thank you all for the quick response.

Yes, killing the transactions would be the last option and i think i will
have to wait until those transactions finish and all first undo tablespace
segments offline.

Riyaj - My fast_start_parallel_rollback has been set to LOW (default, i
guess). And following is the result for the USED_UBLK and USED_UREC for the
respective sessions.

SQL> select d.used_ublk, d.used_urec, a.usn, e.sid from v$rollname a,
v$rollstat b, dba_rollback_segs c, v$transaction d, v$session e where
a.usn=b.usn and and a.usn=d.xidusn and d.addr=e.taddrand
b.status in ('PENDING OFFLINE','UNKNOWN');

----------               ----------            ----------    ----------
        1                    2                    20        22
      692            60955                   37         16
      386            29993                    4         34

What could be infered from this USED_UBLK and USED_UREC in this case?


On 5/31/07, Ted Coyle <oracle-l@xxxxxxxxxxxx> wrote:

The rollback may be huge and it might take longer than waiting for it to
complete.  Just a thought.

Safe is relative.  I don't think anyone can answer if it is safe to kill
long running on your system from the app perspective, but I think it is
Oracle/technically safe.

I use the same undo reduction process in production warehouses, but I've
never done by killing sessions.

. The only option i see here is to kill the session (22,16,34), which will
offline all the undo segments and then drop the first undo tablespace. This
is a production box, so just wanted to confirm with you. Is it safe to go
ahead and kill the session? is there any other work around in this case for
dropping the first undo tablespace. "


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