Why is query optimization important?

DBA need query optimization?

• Answer:

  Data is inserted into a database. Users need to get information from the database. These requests are called "queries". Data is continually being inserted into the tables in the database. There is a utility called "update statistics" which gathers information from the table and feeds is to the "query optimizer". The query optimizer, based on information gathered from update statistics, chooses the most efficient path to gather the data for the user and return the results as quickly as possible. How often statistics must be updated is completely dependent upon the frequency and quantity of updates/inserts/deletes into the table. If the table is static (unchanged), then once update stats is ran, there is no need to run it again.