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Friday, January 29, 2021

About SQL Hints

About SQL Hints


* A hint is an instruction to the optimizer to follow an ‘application developer desired’ execution plan 

* Make decisions for the optimizer because you have more in-depth knowledge about data distribution patterns

* In a test or development environments, hints are useful for testing the performance of a specific access path- test use of a specific index when there are several indexes defined on the same table 

* Changes in the database or host environment can make hints obsolete and  even have negative consequences

* Recommended to use tools like SQL Tuning Advisor, SQL plan management, and SQL Performance Analyzer, to address performance problems not solved by the optimizer before considering hints

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