User-defined statistics for UDTs

Because information about the nature and use of a user-defined data type (UDT) is not available to the database server, it cannot collect distributions or the colmin and colmax information (found in the syscolumns system catalog table) for a UDT. Instead, you can create a special function that populates these statistics.

The database server runs the statistics collection function when you execute UPDATE STATISTICS.

For more information about the importance of updating statistics, see Statistics held for the table and index. For information about improving performance, see Updating statistics for columns with user-defined data types.