Help: Strange behaviour when using parallel

Thank for those who helped me to solved puzzal.

I have another question,
Here is my create index statement

 create index sensor_data
 on sensor_data_2000 (data_id,sensor_id)  local
 storage (initial 200m next 200m pctincrease 0)  tablespace indx
 nologging
 parallel (degree 2)

To my surprise, I found that there are two sessions which is using rollback segment, is it something strange?

I thought create index only use temp tablespace. Is it because of the parallel? Will it slow down because of the extra I/O?

Thanks for your help.  

-- 
Sent  by joebayerii from hotmail  included in com
This is a spam protected message. Please answer with reference header.
Posted via http://www.usenet-replayer.com/cgi/content/new