Statistics for expression-based indexes
In an expression-based index, the key includes one or more expressions that consist of more than just a column name. An expression-based index can provide faster and more efficient access to data. However, before you implement this feature, consider how statistics are collected for expression-based indexes.
To benefit from expression-based indexes, you do not have to carry out any special activities. Statistics for expression-based key columns are collected along with other statistics on the table and its indexes. Typically, the same options that you apply to a table's columns are also suitable for the expression-based key columns. However, if you want to have more control, review the following topics: