Do you have a bug number for that one? We do use ASSM. On Wed, May 7, 2008 at 7:24 AM, Anjo Kolk <anjo.kolk@xxxxxxxxxxx> wrote: > May be related: > > I have a merge statement that sometimes hangs. In fact the Oracle shadow > is consuming CPU but it doesn't get accounted for in V$sesstat / v$sysstat > (haven't checked that but I believe that to be the case). So I see this > shadow process consuming CPU, I took gdb and attached my self and took a > stack trace. I found that the merge was doing an insert and for that it had > to find more space in the index. While finding the space it seems to be in a > tight loop in the space management code for bitmap segments (ASSM). The > workaround from Oracle is to not use ASSM for the Index. So if your case one > of the slaves (or coordinators) hits this problem it won't sent a > completition message to the coordinator. This then could result in the > behavior that you see. > > Anjo. > > > > On 5/6/08, John Smith <john40855@xxxxxxxxx> wrote: > > > I have been working with an AIX LPAR which has access to 6 CPU's, > > defaults to 3. Its primarily a data warehouse instance, so we enabled > > parallel on it and about half of the tables are large, and are > > range-partitioned on by year, and in some cases sub-partitioned on > > accounting period (list method). > > > > There is plenty of memory (32G), and its on an EMC Clariion storage. > > However, when we run loads using merge, and in some cases, some very large > > queries, the queries run for days at a time, but the CPU usage is not all > > that high (rarely above about 60%). > > > > The AWR report (its oracle 10.2.0.3) shows a huge number of wait events > > on PX Dequeue Credit: Send Blkd. According to the oracle documentation, > > this is an idle event, but it appears to me that about 2/3 of the available > > time is spent waiting on this event. Has anyone seen this, or have any idea > > how to track down what is causing the problem? There are also a large > > number of IO wait events, but the time is not significant compared to the PX > > wait event. Is it possible that PX wait event is caused by the IO wait > > event? If so, how could I track it down? > > > > > > -- > Anjo Kolk > Owner and Founder OraPerf Projects > tel: +31-577-712000 > mob: +31-6-55340888 >