For SQL Server performance tuning, besides rebuild index and update statistics, often we also need to identify missing indexes. This can be done from SQL Tuning Advisor, but I personally feel it’s quicker to directly query the dynamic management views. Here is a sample query I normally use to identify and generate index creation scripts from DM views.
Please feel free to comment, if there are better ways.
SELECT
migs.avg_total_user_cost * (migs.avg_user_impact / 100.0) * (migs.user_seeks + migs.user_scans) AS improvement_measure,
CAST('
CREATE INDEX [missing_index_' + CONVERT (varchar, mig.index_group_handle) + '' + CONVERT (varchar, mid.index_handle) + '' + LEFT (PARSENAME(mid.statement, 1), 32) + ']'
+ ' ON ' + mid.statement
+ ' (' + ISNULL (mid.equality_columns,'')
+ CASE WHEN mid.equality_columns IS NOT NULL AND mid.inequality_columns IS NOT NULL THEN ',' ELSE '' END
+ ISNULL (mid.inequality_columns, '')
+ ')'
+ ISNULL (' INCLUDE (' + mid.included_columns + ')', '')
AS VARCHAR(MAX)) AS create_index_statement,
DB_Name(mid.database_id) DatabaseName,
Object_Name(mid.object_id,mid.database_id) TableName,
migs.group_handle,
migs.unique_compiles,
migs.user_seeks,
migs.user_scans,
migs.last_user_seek,
migs.last_user_scan,
migs.avg_total_user_cost,
migs.avg_user_impact,
migs.system_seeks,
migs.system_scans,
migs.last_system_seek,
migs.last_system_scan,
migs.avg_total_system_cost,
migs.avg_system_impact
FROM sys.dm_db_missing_index_groups mig
INNER JOIN sys.dm_db_missing_index_group_stats migs ON migs.group_handle = mig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details mid ON mig.index_handle = mid.index_handle
WHERE migs.avg_total_user_cost * (migs.avg_user_impact / 100.0) * (migs.user_seeks + migs.user_scans) > 10
AND db_name(mid.database_id) in ('SECURITY', 'PERFORM', 'HOLDING','RULES')
AND avg_user_impact > 50 -- Estimated performance impact
AND last_user_seek > DATEADD(hour,-48,GETDATE())
ORDER BY
migs.avg_total_user_cost DESC, migs.avg_user_impact DESC