RE: Enqueue type - RO-Multiple Object Reuse (fast object reuse)

  • From: "Khedr, Waleed" <Waleed.Khedr@xxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Wed, 31 Aug 2005 17:39:43 -0400

Do you use parallelism (PQO) while reading tables that might have been
loaded/updated before/during the reads?


-----Original Message-----
From: Keith Moore [mailto:kmoore@xxxxxxxxxxxx] 
Sent: Wednesday, August 31, 2005 3:35 PM
To: rshamsud@xxxxxxxxxxxx
Cc: kmoore@xxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: Re: Enqueue type - RO-Multiple Object Reuse (fast object reuse)


The database is version

The strange thing is that no objects are being dropped. And certainly
5180 times, like statspack shows.

Could this be a bug that would fix? We have a strange situation
here where the Sysadmin installs the softwarwe and then I take over.
been trying to get him to upgrade to, but without success.

It also makes it interesting when something doesn't work and you have to
figure out what he might have done wrong.


> Keith
>     RO enqueue is acquired while dropping/truncating the objects. Drop
> /truncate will post the DBWR to flush the buffers associated with
> objects. While DBWR is performing this operation, foreground process
> will wait for RO enqueue. Usually RO can be seen with CI (Cross
> 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
> to be a stable release.
> Thanks
> Riyaj "Re-yas" Shamsudeen
> Certified Oracle DBA (ver 7.0 - 9i)
> Allocation & Assortment planning systems
> JCPenney
> 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
>>instance with 3 minutes of wait time during a 12 minute test.
>>Interestingly, it has less than one second of wait on the other
>>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.
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