Starting with Oracle Database 10g, each latch of significance has its own wait event. If you want to know the total latch-related time, you'll need to sum the individual latch times. Usually, this is not necessary, even with severe latch contention, because one latch will dominate and be your main focal point.

In Figure 2-16, the top non-IO wait event is library cache latch contention. Is this an issue? While 85% of the non-IO wait time is related to library cache latch contention, the 5 seconds it consumes, compared to the total wait time of 621 seconds, are insignificant.

To help in analyzing the application, the report captures the SQL directly affecting the response times and shows its resource consumption. As Figure 2-16 shows, only the SQL identifier and key performance attributes appear in the report. For performance reasons, the actual SQL statement text is not collected.