MultiColumn Statistics

A similar real-world problem exists with SQL predicates which reference multiple columns as that explained for SQL expressions and functions. And a similar solution regarding extended statistics collection is required in order to correct such problems.

Selectivity & Multiple Column Predicates

Whether this issue arises or not is dependent upon the data model in use and the nature of the queries which might be submitted in such an environment. But in general, we can say that query selectivity is based upon the population characteristics of the column values. Based upon the various techniques for Optimizer statistics collection which we have discussed, one has the means to ensure that the selectivity estimates will be accurate.