I have the below query :
select /*+parallel(4)*/ ---> First Location <Desc_1> Amount, <Desc_2> Amount, <Desc_3> Amount from (select /*+parallel(4)*/ ---> Second Location <Column_1>, <Column_2> from <Example_Table> where <Conditions> ) pivot(sum(Column_1) Amount for <Column_2> in (1 as <Desc_1>, 2 as <Desc_2>, 3 as <Desc_3>) );
The point is that
<Example_Table> is a very big table and I want to ask where is the best to location to use the
/*+parallel(4)*/ ? Is it better to use it in the
Subquery or in the outer select? What if we use
/*+parallel(4)*/ in both outer and inner select? Is it bad for performance?