Hi I have done that already but still. But I just find out the possible cause after doing several tests. The row cache is caused by space allocation when several PX slaves are inserting into several subpartitions, I noticed this after running two insert append, the first had tons of row cache waits and the second insert cero. Looks like expected behaviour but in a 6 nodes RAC this look like a killer. Thanks -- LSC On Sat, Dec 19, 2009 at 7:01 PM, Greg Rahn <greg@xxxxxxxxxxxxxxxxxx> wrote: > I dont recall the bug# but there is an issue related to quotas that > can show when there are a relatively high number of concurrent PX > sessions inserting into the same tablespace. The work around is to do > a direct grant (dba or unlimited quota sys priv is not sufficient). > alter user <name> quota unlimited on <ts>; > > That may be enough for you to find the bug (look for the dc row cache > stuff also). > > Hope that helps. > > On Fri, Dec 18, 2009 at 11:58 PM, LS Cheng <exriscer@xxxxxxxxx> wrote: > > > > The insert is simply insert append into... select, the degree of > parallelism > > is 8 for some tables, 4 for others and 2 for smaller tables. I can > observe > > that when there are 5 of these inserts running concurrently all of them > > suffers high contention on row cache lock, specifically dc_object_ids and > > dc_segments. Previously the load processes ran without parallel DML and > > yesterday pdml was enabled. Same symptoms. > > -- > Regards, > Greg Rahn > http://structureddata.org >