Auto Update Stats Disabled

SQL Server maintains statistics that help it decide how to build better execution plans.  It periodically reviews the content of tables, updates its statistics about the distribution of data in fields, and uses that for execution plans.  By default, this happens automatically – statistics are updated when about 20% of the data in a table changes. We check sys.databases looking for databases where auto-update-stats has been turned off.

But… My Vendor Told Me to Leave This Disabled

There are rare edge cases where we don’t want statistics to change even though the data has changed. If the application was written and tested with this setting off and it has built in tools to manage update of its statistics, it’s OK to leave this off.

But if you’re not absolutely sure that this is helping performance instead of hurting it, you’ve got a problem.

To Fix the Problem

In SQL Server Management Studio, you can right-click on each database and go into its properties to change Auto Update Stats to Enabled. This takes effect immediately for queries executed from this point forward.

After the change, you can monitor overall system performance looking for improvements, especially around query execution plans.