Figure 3-10 shows a classic wait event report based on the Oracle Database 10g v$system_event view. The same information can be found near the top of both a Statspack (Figure 3-13) and an AWR report. Since the top wait event is clearly the CBC latch, we know there is significant latch contention, and we know the specific latch.

Figure 3-10. The v$system_event based OSM swpctx.sql report. Clearly, latch contention is significant, and the latch to focus on is the CBC latch.

Figure 3-11. The v$session_wait-based OSM swswp.sql report details sessions currently posting a wait event containing latch%free. We caught three sessions waiting for latch number 116, which the second v$latchname-based query shows as being the CBC latch. We know this is a pre-10g system because the latch name is not part of the wait event.