Oracle Performance Optimization Operations IX: masking useless indexes

Continue with the example of Oracle performance optimization Operation eight

Because there are queries involving disposalcourseflag=6 in the actual query, it would be very unwise and inefficient to use the index on that field at this point.

So in this case, we need to mask the index in a special way so that Oracle chooses the index on the other field.

For example, if the field is numeric, just after the field name of the expression, add "+ 0" for the character type and the string above: | | ""

Such as:

SELECT * from  serviceinfo where disposalcourseflag+ 0 = 6 and Workno =  ' 36 ';

However, do not screen out the index that is used, otherwise it will produce a low-efficiency full-table scan.

Oracle Performance Optimization Operations IX: masking useless indexes