SQL Server 2005 Performance Dashboard Reports - Professional SQL Server 2005 Performance Tuning - page 491

MissingIndexes
In SQL Server 2005, when the query optimizer performs an operation like a table scan and detects that
an index that is not present would be useful for that statement, it forms an index recommendation. This
recommendation can be accessed from two places:

❑ Missing index DMVs

❑ Showplan XML

The Missing Indexes report combines data from three of the missing index DMVs (Sys.dm_db_missing_
index_details, sys.dm_db_missing_index_groups, and sys.dm_db_missing_index_group_stats) to show
you what statements could have benefited from an index. In addition to the statement, it also shows
the percentage estimate cost for maintaining the index and estimated benefit for using the index (see
Figure 13-19).

Figure 13-19

Unlike the Database Engine Tuning Advisor, these index recommendations from the Performance Dash-
board Reports only take in the statement being executed in its current context. This does not account for
the amount of work to maintain the index.