Figure 3-13. A partial Statspack report based on Oracle9i Release 2. Only the Top 5 Timed Events section and the most active latches in the Latch Sleep Breakdown section are shown.

Table 3-2 is based on the Latch Sleep Breakdown section in Figure 3-13. The Impact column and the impact percentage were calculated, and the rows were sorted by the impact in descending order. Clearly, the library cache is the top latch and should be given priority. But in this case, the shared pool latch should also be addressed. So, the first priority is the library cache latch, followed by the shared pool latch. As you'll learn in Chapter 7, the library cache and shared pool latches are closely associated with cursor execution, so a change focused on one can affect the other.

In addition to the sleeps information in v$latch, the v$latch_misses view contains additional information. One key piece of potentially helpful information is the location (column location) of the latch within the kernel code. This can provide useful information when searching MetaLink or Google for solution clues.