CPU and Disk Skew

Database
Enthusiast

CPU and Disk Skew

Hi,

Can anyone please provide some clue about the reason for the following performance issues.

1) 

High cpu and disk skew when the explain step in PMON shows the spool merge during the final step of a parallel block operation. This step is uaually showing a CPU Skew and Disk Skew varying from 80%-98%. We have not defined a join index on the underlying tables.

2)

I could also see a high CPU skew while invoking TPT load utilites through Datastage. We have not yet defined number of sessions for the load utilities. Does this lead to high CPU skew (no disk skew in this case).

Thanks in Advance.