Manually Tuning SQL

Abstract

It has been said many times in books, articles, and other publications that over 90% of all performance problems on a database are due to poorly written SQL. Often, database administrators are given the task of “fixing the database” when queries are not performing adequately. The database administrator is often guilty before proven innocent—and often has the task of proving that a performance problem is not the database itself but, rather, simply, SQL statements that are not written efficiently. The goal, of course, is to have SQL statements written efficiently the first time. This chapter’s focus is to help monitor and analyze existing queries to help show why they may be underperforming, as well as show some steps to improve queries.