How does query processing and query optimization related?

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 Query processing and optimization are a fundamental, if not critical, part of any DBMS. To be utilized effectively, the results of queries must be available in the timeframe needed by the submitting user—be it a person, robotic assembly machine, or even another distinct and separate DBMS. 

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Maintaining large databases with high performance is called database query optimization. A distributed database is a group of autonomous cooperating centralized databases, in that query processing requires transferring data from one system to another through a communication network. In the query optimization process, the cost is always associated with each and every query execution plan (QEP).



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