In parallel with updating
Updates query optimization statistics on a table or indexed view.
By default, the query optimizer already updates statistics as necessary to improve the query plan; in some cases you can improve query performance by using UPDATE STATISTICS or the stored procedure sp_updatestats to update statistics more frequently than the default updates.
However, certain workloads that are sensitive to widely varying data distributions may require an increased sample size, or even a full scan.
For more information, see the CSS SQL Escalation Services blog.
SAMPLE is useful for special cases in which the query plan, based on default sampling, is not optimal.When 0 PERCENT or ROWS is specified, the statistics object is updated but does not contain statistics data.For most workloads, a full scan is not required, and default sampling is adequate.0 (default) Uses the actual number of processors or fewer based on the current system workload.For information about how to update statistics for all user-defined and internal tables in the database, see the stored procedure sp_updatestats (Transact-SQL).