how does truncate table work?

Dear Gurus,

I am new with oracle database but strong experience with informix . In one of the oracle training which i have recently involved , the lecturer asked the difference between delete and truncate table. Although i did not exactly know , i can guess that , truncate table runs fast because instead of deleting each records , it can invalidate the table by cahnging a flag in data file headers or etc. ( thinking of informix architecture) But the lecturer said truncate table also deleted records but did not generate redo log data thats why it was faster.

Is it possible to be very fast for example deleting 100000000 rows without creating redo log entry. I had better drop & create it?

I will be appreciate if someone comments about this.

Kind Regards,
hope Received on Tue Aug 19 2003 - 01:00:56 CDT