Query Design Analysis

Abstract

A database schema may include a number of performance-enhancement features such as indexes, statistics, and stored procedures. But none of these features guarantees good performance if your queries are written badly in the first place. The SQL queries may not be able to use the available indexes effectively. The structure of the SQL queries may add avoidable overhead to the query cost. Queries may be attempting to deal with data in a row-by-row fashion (or to quote Jeff Moden, Row By Agonizing Row, which is abbreviated to RBAR and pronounced “reebar”) instead of in logical sets. To improve the performance of a database application, it is important to understand the cost associated with varying ways of writing a query.