When a valid SQL statement is fired , the oracle database have to decide its plan in order to retrieve the necessary data requested by the query.
This decision can be made by the using the following methods mention below :
Rule Based Optimizer (RBO) : Optimization is done via a set of rules,distribution of data is not taken into account.
Cost Based Optimizer (CBO) : Execution plan is calculated by taking into account the distribution of data. Requires analysis of tables and indexes (DBMS_STATS)
This decision can be made by the using the following methods mention below :
Rule Based Optimizer (RBO) : Optimization is done via a set of rules,distribution of data is not taken into account.
Cost Based Optimizer (CBO) : Execution plan is calculated by taking into account the distribution of data. Requires analysis of tables and indexes (DBMS_STATS)
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