What is the goal of query optimization Why it is important?

The goal of query optimization is to reduce the system resources required to fulfill a query, and ultimately provide the user with the correct result set faster. Query optimization is important for at least a few reasons. First, it provides the user with faster results, which makes the application seem faster to the user. Secondly, it allows the system to service more queries in the same amount of time, because each request takes less time than unoptimized queries. Thirdly, query optimization ultimately reduces the amount of wear on the hardware (e.g. disk drives), and allows the server to run more efficiently (e.g. lower power consumption, less memory usage).