Beginning Oracle Database 11g Administration From Novice to Professional

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CHAPTER 17 SQL TUNING
Another way to identify tuning candidates is to examine a STATSPACK report.
STATSPACK reports were discussed in Chapter 16.
Understanding the Causes of Inefficient SQL
We may not even realize that we are dealing with inefficient SQL because powerful hardware
can compensate for much inefficiency. In fact, one simple method of “improving”
performance is simply to throw powerful hardware at the problem. 1 In other cases,
a statement may take such little time to execute that we may not realize that it is inefficient.
There are many different causes for poor performance of SQL statements, and
there are many solutions; a short essay cannot do them justice.
We should also keep in mind that, given enough time, effort, and money, it is always
possible to extract more performance out of an SQL statement. The example used in this
chapter perfectly illustrates the point; we keep improving its performance until we hit the
theoretical maximum level of performance. However, it is not usually possible to give so
1. In Oracle on VMware, Dr. Bert Scalzo makes a persuasive case for “solving” problems with hardware
upgrades, saying that "Person hours cost so much more now than computer hardware even with inexpensive
offshore outsourcing. It is now considered a sound business decision these days to throw cheap
hardware at problems."