statspack , LAG - does this look OK

Greetings
Please see the sql and the out put, have a few questions (Orale 8.1.7.4 and 9i Rel2, will be doing the same for 10g also): Want to send this as a report for DEV team on how we are doing with DB:

I am calculating per minute values.
STATSPACK Report shows these values, but I have to pull the report every hour and compile them to show this info.

1. Am I doing it right
2. Is it efficent or is there a better way to do this
3. See some negative values, I am guessing the previous values were higher than the present, what do I do in such cases 4, Does the numbers make sense or am I wasting my time on this
4. If this is OK, planning to add CPU used by this session, db block gets, consistent gets, physical reads
5. How can I add consistent gets+ db block get to show LIO
6. Does it make sense to put these values in columns, if Yes, How

Apprecite your Help
**
*select snap_time, name, round( (value -lag(value) over (order by s.snap_id)
)/

round( (SNAP_TIME - lag(SNAP_TIME) over (ORDER BY s.snap_id))* 1440 * 60/60,0), 0) "Per Min"
from stats$sysstat s, stats$snapshot t
where
-- trunc(t.SNAP_TIME)=trunc(sysdate) and s.SNAP_ID=t.SNAP_ID and
name = 'user commits'
UNION ALL
select snap_time, name, round( (value -lag(value) over (order by s.snap_id)
)/

round( (SNAP_TIME - lag(SNAP_TIME) over (ORDER BY s.snap_id))* 1440 * 60/60,0), 0) "Per Min"
from stats$sysstat s, stats$snapshot t
where
-- trunc(t.SNAP_TIME)=trunc(sysdate) and s.SNAP_ID=t.SNAP_ID and
name = 'user rollbacks'
UNION ALL
select snap_time, name, round( (value -lag(value) over (order by s.snap_id)
)/

round( (SNAP_TIME - lag(SNAP_TIME) over (ORDER BY s.snap_id))* 1440 * 60/60,0), 0) "Per Min"
from stats$sysstat s, stats$snapshot t
where
-- trunc(t.SNAP_TIME)=trunc(sysdate) and s.SNAP_ID=t.SNAP_ID and
name = 'physical writes'
ORDER BY SNAP_TIME, NAME
/*

OutPut :

SNAP_TIME           NAME                    Per Min
------------------- -------------------- ----------

09/07/2007 09:24:19 physical writes
                    user commits
                    user rollbacks

09/07/2007 09:49:58 physical writes            6985
                    user commits               1128
                    user rollbacks              358

...

10/24/2007 10:39:50 physical writes           -5782
                    user commits              -1336
                    user rollbacks             -876

10/25/2007 08:18:29 physical writes            2370
                    user commits               1665
                    user rollbacks             2750

10/25/2007 08:24:13 physical writes            1127
                    user commits               2159
                    user rollbacks             3927

10/25/2007 08:32:39 physical writes             752                    #
After the Vender Patch
                    user commits               1374
                    user rollbacks             2777

10/26/2007 08:00:04 physical writes              73
                    user commits                427
                    user rollbacks             1416

10/26/2007 09:00:05 physical writes             182
                    user commits                696
                    user rollbacks             2104

10/26/2007 10:00:05 physical writes             203
                    user commits                454
                    user rollbacks             1512

-
Regards & Thanks
BN

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