Avoid arithmetic expressions

 

Do not use an arithmetic expression as an operand to be compared to a column in a row selection predicate. The optimizer does not use an index on a column that is being compared to an arithmetic expression. While this may not cause an index over the column to become unusable, it will prevent any estimates and possibly the use of index scan-key positioning on the index. The primary thing that is lost is the ability to use and extract any statistics that might be useful in the optimization of the query.

For example, when using SQL, specify the following:

… WHERE SALARY > 16500             

instead of

… WHERE SALARY > 15000*1.1 

 

Parent topic:

Coding for effective indexes