Query Optimization

Query Optimization

Activity of selecting an efficient execution strategy for processing query.

1. As there are many equivalent transformations of same high-level query, purpose of Query Optimization is to choose one that minimizes resource usage.
2. Generally, decrease total execution time of query.
3. Problem computationally intractable with large number of relations, therefore strategy adopted is actually decreased to finding near optimum solution

Query Optimization Techniques

The query processor optimizes queries which are created on the databases. However, this particular optimization is restricted towards the information that the query processor knows about in the databases and the organization of the databases.

Write effective queries as well as determine logical tables to maximize query performance. Query optimization is based on the extent to which the database or file system performs the filtering that is required to obtain the final result set.