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 -- //www.freelists.org/webpage/oracle-l