A Study on the Role of Equivalence Rules in the Enhancement of Query Performance
Tejy Johnson · 2013
For the past decade many research and development work had been carried out in the area of Query processing. As Query Processing is an important concept in database technology. In Query Processing one of the most critical and important step is Query Optimization. Many Query Optimization algorithms, techniques and methods have been evolved to optimize a query efficiently. In spite of all these techniques and methods, optimizing a query accurately was not possible. The main reason behind this was, we required sufficient information to determine which technique would be most effective. To determine this was a difficult task. This problem can be solved by understanding the fact that one aspect of optimization occurs at the relational algebra level where the system attempts to find an expression that is equivalent to the given expression, but more efficient to execute. To transform a given expression into an equivalent one we can make use of Equivalence Rules. We can use these rules to generate systematically all expressions equivalent to the given query. This paper focuses on new directions in the area of Query Optimization. Here we have discussed about the vital role of Equivalence Rules in optimizing a query efficiently. In this paper we have also briefly discussed about the cost estimation which is one of the factors that influences query performance. Here we have also given some best practices that have to be considered in reducing the Execution Cost of a query.