Re: What is lock type 'KO' in v$lock table?

From: Bart The Bear <bartthebear_at_gmail.com>
Date: Sat, 23 Sep 2006 00:18:34 GMT
Message-Id: <pan.2006.09.23.00.18.33.892138@gmail.com>

On Fri, 22 Sep 2006 17:10:00 -0700, Charles Hooper wrote:

> Bart the bear wrote:

>> Charles Hooper wrote:
>> > Bart the bear wrote:
>> > > Does anyboy know?
>> >
>> > Try here for an answer:
>> > http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14237/enqueues.htm
>> >
>> > Maybe this SQL statement will help:
>> > SELECT
>> >   *
>> > FROM
>> >   V$LOCKED_OBJECT;
>>
>> It doesn't tell me anything. What the heck is "multiple objects
>> checkpoint"?

>
> A search of Metalink and other documentation fails to provide a
> definition of "multiple object checkpoint", as does a Google search.
> Given the amount of information that you have provided, the only
> suggestion that I can offer is to interpret the phase literally - there
> are more than one table, index, or other object that is waiting for a
> checkpoint to complete.
>
> Are you using RAC? Are you trying to determine how fast the database
> instance can recover from a SHUTDOWN ABORT? Does the server have 256MB
> of memory, while you have allocated 1.5GB to the database buffer cache,
> you have redo logs set at 5MB each, and are trying to perform a full
> table scan on a table that is 2GB in size?
>
> What is happening in the system before you see the lock type "KO" in
> the V$LOCK view? Have you checked the alert log, or looked for bdump
> or udump logs?

Charles, here is what happens:

I have a script which has to update ~60M rows. I had to kill it and re-start it. The new incarnation did not wait for a bunch of TX locks, it was waiting for the following event:

ENQ: KO - fast object checkpoint

Surprisingly enough, this lock was held by the CKPT process, not PMON, as I've expected. Very few undo blocks were actually consumed in v$undostat. My question is what is "fast object checkpoint" and is there a new method of reclaiming resources held by murdered transactions? Is it documented anywhere? Received on Fri Sep 22 2006 - 19:18:34 CDT