Since the beginning, I/O has been one of the main determining factors for overall performance. I/O can easily surpass all other considerations, particularly if an SQL statement asks for a very large result or a missing index causes the scan of a very large table.
”. Overthinking and trying to predict Db2 performance is a slippery slope, and so rather than “thinking” about Db2 performance why not have the database tell you how it will perform. The key to this is the Db2 accounting trace, and subsequent Db2 accounting reports. The accounting reports are useful