Which parameter is NOT required when using the WHERE EXISTS clause?

In the context of using the WHERE EXISTS clause in Qlik Sense, the optimization flag is not a mandatory parameter. The WHERE EXISTS function is primarily concerned with assessing whether a specified field in one data set corresponds with a value in another data set.

The two required elements in this clause are the field to check for occurrences and the value to compare against. These elements are essential because, without specifying which field you are examining and what value you are looking for, the function would lack the necessary criteria to execute the existence check effectively.

The optimization flag, on the other hand, serves as a performance tool but does not impact the fundamental operation of the WHERE EXISTS clause. Thus, it is not obligatory to include it for the function to execute properly, making it the correct choice.