How statistics are used for SARGS

When you create an index, statistics are generated and stored in system tables. Some of the statistics relevant to determining the cost of search arguments and joins are:

Only a subset of these statistics (the number of leaf pages, for example) are maintained during query processing. Other statistics are updated only when you run update statistics or when you drop and re-create the index. You can display these statistics using optdiag.

See Chapter 37, “Statistics Tables and Displaying Statistics with optdiag.”