Almost all applications use database and Information Retrieval system for storing and retrieving operational data i.e. query processing. But in current time most of the users on internet are not interested in huge amount of results. They look for specific type of information with in short time that can be retrieving after resolving cardinality estimation. The new challenge requires several changes that vary from introducing new query language constructs to enhancing the query processing and

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... mization engines with new query operators. This paper presented a survey of query optimization.