When hit database load problems, I always want to know what the active sessions are doing and waiting. On 10g we can get these information from V$SESSION view, on 8i and 9i, we can join V$SESSION and V$SESSION_WAIT. Just as following, "event-sql_hash_value-sess_count".
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10/30-20:02:37 205:2815233029:1, 372:4160993935:1
10/30-20:02:47 205:1623840268:1, 372:1569451005:1, 372:4160993935:1
10/30-20:02:57 205:374916427:1, 372:3179818757:1, 372:4160993935:1
10/30-20:03:07 205:1623840268:1, 372:860679981:1, 372:4160993935:1
10/30-20:03:17 372:4160993935:1
10/30-20:03:27 372:270817213:1, 372:4160993935:1
10/30-20:03:37 372:4160993935:1
......
The oramon utility get these information at 10 seconds frequency. So we can track back, when the load spike, which SQL cause the problem, or which wait event cause the problem. Actually, this is the most useful information for a sudden load spike case.