Parallel Execution of UPDATE STATISTICS

The database server executes the SQL statement UPDATE STATISTICS in two phases. The optimizer first scans the table, then sorts the result.

• If the table is fragmented across dbspaces on different disks, parallel scans can occur.
• When you execute UPDATE STATISTICS in MEDIUM or HIGH mode, the optimizer sorts the data for each column to obtain data distributions. The sorts can also be executed in parallel.

For more information about efficient use of UPDATE STATISTICS, see Create and Maintain Data-Distribution Statistics.