Re: Shutdown Abort

  • From: amit poddar <amit.poddar@xxxxxxxx>
  • To: jeremiah@xxxxxxxxxxx
  • Date: Tue, 03 Jul 2007 14:58:05 -0400

Hi jeremiah,

from your link

"When
trying to apply a DDL change to some segments, a DBA may encounter the error ORA-00054: resource busy and acquire with NOWAIT specified. *This can occur even if the DBA acquires an exclusive DML lock on the table using the lock table command. U*nfortunately, locking a table does not guarantee the success of
any subsequent DDL statement on the table or associated index"

I thought that DDL commits twice once before it starts and second after it completes. So even if you obtain exclusive DML lock on a table/index the first commit will release the lock. So obtaining a exclusive preemptive DML lock would not be possible.

Please correct me if I am wrong.

amit

Jeremiah Wilton wrote:
Thanks Jared. It has taken all of my strength to not reply to some of the most egregious postings in this thread. My more recent blurb on shutdown abort can be found on page four of my 2004 HA paper:

http://www.ora-600.net/articles/stayinalive.pdf

I will confirm that practically every site that requires very high availability uses 'abort' as SOP. I am really surprised and disappointed by the wild theoretical conjecture that accompanies the steadfast resistance to 'abort'.

Speaking of wild theoretical conjecture, thanks to Alex G. for his recent rants on DBAs and guessing. I have long been an opponent of the 'guessing method' of Oracle tuning, which goes hand in hand with the 'try a bunch of stuff' method of Oracle troubleshooting :-)

Best to all, including the guessers,

Jeremiah Wilton
ORA-600 Consulting
http://www.ora-600.net

Jared Still wrote:

Please see http://www.speakeasy.org/~jwilton/oracle/shutdown-abort-bad.html

If you are not familiar with Jeremiah Wilton, he was a DBA at Amazon.com <http://Amazon.com> from early days.

Amazon has a few databases, and they were/are regularly shutdown with abort.
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