Keith
RO enqueue is acquired while dropping/truncating the objects. Drop
/truncate will post the DBWR to flush the buffers associated with those
objects. While DBWR is performing this operation, foreground process
will wait for RO enqueue. Usually RO can be seen with CI (Cross Instance
invalidation ) enqueues even in non-rac single instances
One of the primary reason is that DBWR is slow or buffer cache is
too big.
What is surprising though, this behavior is very visible up to 9i.
But, in 10g, drop will simply rename the objects ( for flashback
feature). Clearing the recycle bin will take care of flushing the
buffers and so this is not a bigger issue anymore. Did you disable the
flashback feature by any chance ?
BTW, 10.0.3 looks too low of a version. So, far I have seen 10.1.0.4
to be a stable release.
Thanks
Keith Moore wrote:
Does anyone have information on this?
We have setup a two node 10g RAC database, Oracle version 10.0.3.
I ran statspack for a test and this shows up as the top wait time in one instance with 3 minutes of wait time during a 12 minute test. Interestingly, it has less than one second of wait on the other instance.
Here is the statspack info:
Enqueue Type (Request Reason) ------------------------------------------------------------------------------ Requests Succ Gets Failed Gets Waits Wt Time (s) Av Wt Time(ms) ------------ ------------ ----------- ----------- ------------ -------------- RO-Multiple Object Reuse (fast object reuse) 5,180 5,180 0 2,217 184 83.00 TX-Transaction (row lock contention) 23 23 0 23 1 49.57
Any help would be greatly appreciated.
Keith
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