What is Query Processing ?

 Ans-:

Query Processing and Optimization 

Query Processing

Query Processing is a procedure of transforming a high-level query (such as SQL) into a correct and efficient execution plan expressed in low-level language. A query processing selects a most appropriate plan that is used in responding to a database request. When a database system receives a query for update or retrieval of information, it goes through a series of compilation steps, called execution plan.

 

Different phases of Query Processing are:

·       In the first phase called syntax checking phase, the system parses the query and checks that it follows the syntax rules or not.

·       It then matches the objects in the query syntax with the view tables and columns listed in the system table.

·       Finally, it performs the appropriate query modification. During this phase, the system validates the user privileges and that the query does not disobey any integrity rules.

·       The execution plan is finally executing to generate a response.