To start the diagnosis, repeatedly sample the buffer busy waits event's p1 and p2 parameters. The p1 parameter is the buffer's file number, and the p2 parameter is the block number. Normally, when you repeatedly sample the p1 and p2 values, they will change, indicating different buffers are being waited upon. It is also common to see a smaller subset of blocks that are related to a specific object, say the employee table. Finally, while rare, but important to notice, is if the same buffer or two always seem to appear. These would be deemed hot blocks. When you repeatedly sample, take note of the parameter values, as they will be used later in our analysis.

Figure 6-25 shows a single sample query providing the parameter details. In this single sample, three processes were waiting for file number 4 and block number 54. Another sample will normally show multiple processes waiting for a different buffer. Once you have a few samples, move on to step 2.

Figure 6-25. This sample v$session_wait-based OSM script swswp.sql displays the session numbers along with their wait event parameters for a given wait event. In this situation, we are looking for buffer busy waits parameter values and parameter value patterns.