Categories
database-performance sql sql-server

What does exec sp_updatestats do?

What is the use of sp_updatestats? Can I run that in the production environment for performance improvement?

sp_updatestats updates all statistics for all tables in the database, where even a single row has changed. It does it using the default sample, meaning it doesn’t scan all rows in the table so it will likely produce less accurate statistics than the alternatives.

If you have a maintenance plan with ‘rebuild indexes’ included, it will also refresh statistics, but more accurate because it scans all rows. No need to rebuild stats after rebuilding indexes.

Manually updating particular statistics object or a table with update statistics command gives you much better control over the process. For automating it, take a look here.

Auto-update fires only when optimizer decides it has to. There was a change in math for 2012: in <2012, auto update was fired for every 500 + 20% change in table rows; in 2012+ it is SQRT(1000 * Table rows). It means it is more frequent on large tables. Temporary tables behave differently, of course.

To conclude, sp_updatestats could actually do more damage than good, and is the least recommendable option.