A second tool that is often used for performance tuning is the trace facility, which captures statistics about the amount of data and the amount of time spent on actions. Such statistics include the following:
Parse, execute, and fetch counts
I/O counts (physical and logical)
Number of rows accessed
Misses on the library cache
The trace facility is not the easiest tool to use. The basic problem is that the trace statistics are written to a file on the operating system. The file can be hard to locate because it may be on the server on which the Oracle installation resides. It also can contain a lot of information. Statistics are placed into this table for everything Oracle does once the trace facility is turned on. It is ...