I have included a small section on sorts in this chapter, describing products, because, in my experience, it is something often neglected by data warehouse designers and yet can have a profound effect on the performance, particularly summarizing and loading.
Sorting inside the database is often very slow. Using sorting programs provided by the operating system can be up to four times faster. Using a high-performance sort utility can be 10 times as fast.
There are also some other useful features that the better sorting utilities provide:
Record selection. This enables some records to be selected while others are ignored.
Summarizing. You can actually produce your daily, weekly, or monthly summaries using nothing more than the sort utility. ...