Sorting Oracle Records by TimeStamp field Question!

From: Mario <mariano.gagliardi_at_filogix.com>
Date: 20 Nov 2003 06:07:12 -0800
Message-ID: <39c27ec.0311200607.8d4d8d9@posting.google.com>

I have a question regarding the results returned by the following query:

select EVENT_ID, PRIMARY_KEY from EVENT where PTS_CONFIRM = 0 and ROWNUM = 1 order by EVENT_PC

where the index is defined as
CREATE INDEX EVENT_PC ON EVENT (PTS_CONFIRM, CREATE_TIMESTAMP) My question(s) are as follows:
1) Will this not provide me with the oldest record where the PTS_CONFIRM field is zero? I am being told that it cannot guarantee that we will retrieve the oldest record? How is this possible?

2) Secondly, I am told having a timestamp field in an index is an expensive operation is this true? Received on Thu Nov 20 2003 - 08:07:12 CST