Out of date statistics

Detailed Statistics

By default this is not enabled. See below on how to turn this on

Index Manager compares the last usage of the statistics compared to the last updated time.

If the statistics have never been updated a default value of 9,999 is shown in the column Time Diff Usage to Updated.

Order by the column Time Diff Usage to Updated to show the number of days between the statistics used and the statistics updated.

The default filtering is anything over 3 days.

Column	Description
Stats Last Updated	Date statistics were last updated
Stats Usage Last Update	Date statistics were last used
Stats Last Updated (days)	Number of days since statistics were last updated
Stats Last Usage (days)	Number of days since statistics were last used
Time Diff Usage to Updated	Number of days between stats used and updated. a value of 9999 means stats were never updated

Example Output

statsoutofdate

Using the Filter

clip0023

Option	Description
Show Statistics Never Used	Statistics that have not been used.
Show Statistics Not Updated	Statistics never updated. You should review your housekeeping to understand why they have not been updated.
Show Statistics Out of Date	Statistics out of date. In the above example the grid will show statistics where the difference between usage (user queries) and when the statistics were last updated

Detailed Statistics

This applies to SQL Server versions

•SQL Server 2008r2 SP2 or later

•SQL Server 2012 SP1 or later

•SQL Server 2014 onwards

By default Detailed Statistics is turned off. The information is shown in last 6 columns of Statistics: Out of Date tab. The reason for turning this off is it can take a while to collect this information on a SQL Server machine that has recently started/restarted.

statsoutofdatetab

To turn on Detailed statistics. Click on the Detailed Statistics Info button in the setting tab on the ribbon.

detailed statistics

Column	Description
Row Count	Number of rows in the table/indexed view when statistics were updated. Note for filtered indexes the number of rows can be less than the number of rows in the table
Rows Sampled	Number of rows sampled for the statistics
Steps	Number of steps in the histogram
Unfiltered Rows	Total number of rows in the table/indexed view before applying the filter expression for filtered statistics. The number equals the value in the Row Count column for unfiltered indexes
Modification Counter	Number of modifications for the leading statistics column since the statistic was updated. The leading statistics column is the the column on which the histogram is built. Note in SQL Server 2016/SQL Azure the value is the total number of modifications since statistics were updated or the database restarted
Persisted Sample Percent	Statistics updates that do not specify a sampling percentage. A zero value indicates no persisted sample percentage set for the statistic.