Oracle Performance Optimization Operation 10: decomposing complex queries, replacing variables with constants, and optimizing oracle Performance

Oracle Performance Optimization Operation 10: decomposing complex queries, replacing variables with constants, and optimizing oracle Performance

For complex Where condition combinations, Where contains multiple indexed fields, use the IF statement to discuss the situation;

At the same time, remove unnecessary External Parameter conditions to reduce the complexity, so that the index of different fields can be used in different situations.

Continue the "oracle Performance Optimization Operation 9" example.

Where (DisposalCourseFlag <v_DisPosalCourseFlag) or (v_DisPosalCourseFlag is null) and... query,

(V_DisPosalCourseFlag is an input variable. The value range may be [NULL,]). You can use the IF statement to discuss it in different situations.

For example:

IF v_DisPosalCourseFlag = 1 THENWhere DisposalCourseFlag = 1 and... ELSIF v_DisPosalCourseFlag = 2 THENWhere DisposalCourseFlag = 2 and ....