Lokesh M

 Profile Answers by Lokesh M Questions by Lokesh M

• Dec 7th, 2011

 

Oracle optimizer is responsible for handling different situations by making appropriate decisions based on database statistics. It will create route path that is most appropriate to execute the code.

Oracle hints are used when there is a need to instruct or guide the Oracle optimizer to make custom decisions instead of its own decisions which are made based on database statistics.

That means by making use of Hints we are basically giving instruction to the optimizer and telling it which route it should follow to execute the code and thereby affecting the outcome of Oracle optimizer's decision.

Some of the Hint types are as follows:
- Access Hints
- Join Order Hints
- Joint Operations Hints
- Parallel Execution Hints
- Optimization Hints

Jonathan Lewis states that "Hints are interception points in the optimizer code path, and must be obeyed."
and he further adds that "Hint affects the optimizer’s route through its code path."

kalpana

• Oct 28th, 2014

 

Optimizer hints are used with SQL statements to alter execution plans.We are suggesting oracle how the statement should be executed.
syntax : /*+RULE */

Abhijit Musale

• Mar 23rd, 2015

 

To override the flow of execution and priority of the execution we can use oracle optimizer hints.(e.g. PARALLEL,APPEND,etc.)