oracle11g - High CPU utilization during oracle group by -

I suspect the Oracle group section was CPU intensive by the group?

We do not have 32m rows and any index column on a table that connects the group to 7-8 columns and sets them into 3 columns and incorporates them into another table. Sometimes we are seeing the total CPU being used by Oracle processes as 100%.

The query looks something like this:

  select temp_table col1, col2, col3, col4, col5, col6, col7, col8, sum (col10), zodiac ( Calculate (*) computation from orig_table group by col1, col1, col2, col3, col4, col5, col6, col7, col8;   
 As far as I understand, according to the group we have to sort and then group. Will this result in high CPU usage? Besides, what about aggregates? Can they result in high CPU?  
 Thanks in advance.  
  
 
 
 Interpretation scheme will be interesting, look as usual, and if you also ask questions from v $ sql_workarea You will see if the group is spreading on disk or not.  
 This is only the number of rows that you ask is important, but the number of rows that will be the width of the average column for the output and the included column, because it determines to a great extent that the aggregation How much storage is required and thus will spread to the sort disk. If this happens then you may need to increase PGA memory allocation, either manually set or by changing the total PGA size. PGA and SGA buffers should be consulted whether they are in normal shape or not.  
 You may also be the victim of recent trends in server technology, which often presents the CPU with many relatively weak core. Unless you are running parallel queries, you will remain confined to the same core.