Monthly Archives: June 2010

June 2010 Tip of the Month

SQL Server Administration: SQL Server keeps track of indexes that it thinks it needs in order to optimize queries. But there are several “missing index” dynamic management views that give valuable information. Find missing indexes with this query. Always test the suggested indexes, as they do not always help, and are only suggestions.

SELECT mig.index_group_handle, mid.index_handle,

CONVERT (decimal (28,1), migs.avg_total_user_cost * migs.avg_user_impact * (migs.user_seeks + migs.user_scans)) AS improvement_measure,

‘CREATE INDEX missing_index_’ + CONVERT (varchar, mig.index_group_handle) + ‘_’ + CONVERT (varchar, mid.index_handle)

+ ‘ 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 create_index_statement,

migs.*, mid.database_id, mid.[object_id]

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 CONVERT (decimal (28,1), migs.avg_total_user_cost * migs.avg_user_impact * (migs.user_seeks + migs.user_scans)) > 10

ORDER BY migs.avg_total_user_cost * migs.avg_user_impact * (migs.user_seeks + migs.user_scans) DESC