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Friday, January 29, 2021

Reasons Of Changing Execution Plans ?

Reasons Of Changing Execution Plans ?


* Stale or missing statistics 

* Have gathered fresh statistics 

* Optimizer engine has changed after a database upgrade 

* Index has been added or dropped or Table structure has changed

* Database optimizer related  init.ora parameters have been changed 

* Parsed representation of the SQL statement is not in the Library Cache – statements are aged out

* Reparsing the same SQL statement now leads to generation of a new plan 

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