Microsoft SQL Server 2008 collects statistical information about indexes and column data stored in the database. These statistics are used by the SQL Server query optimizer to choose the most efficient plan for retrieving or updating data. This paper describes what data is collected, where it is stored, and which commands create, update, and delete statistics. By default, SQL Server 2008 also creates and updates statistics automatically, when such an operation is considered to be useful. This paper also outlines how these defaults can be changed on different levels (column, table, and database).  Read more...

We look at performing the same task for the sys.dm_db_index_operational_stats Dynamic Management Function (or DMF.) The process is identical, the code is however quite different due to the structural differences between sys.dm_db_index_usage_stats and sys.dm_db_index_operational_stats.  Read more...

In this three-part series I'll look at what you can do to persist this data so you don't find yourself waiting for usage stats to compile over a reasonable period of time just so you can harness the power of the indexing DMOs in your performance tuning process.   Read more...

Statistics update date is stored as metadata on the SQL instance, but after a great deal of research against the system tables and DMVs I realized that this information is not readily exposed to the DBA via any other method than the STATS_DATE() function or the SQL Server Management Studio graphical user interface (GUI).  Read more...

Are you rebuilding statistics twice on your tables? Longtime expert, Andy Warren, shows why you might be asking more work of your SQL Server than is required.  Read more...

When is it okay to let SQL Server to make a statistic for columns in your queries, and when should you take those statistics and make an index out of them? What I do is to test all of my procs, and if they generate system statistics (_WA_SYS%), then I add an index to the table for the column in the statistic. But is this a good practice?  Read more...