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SQLRx® Tip of the Month
 
 
June 2010
Greetings!
 
It goes without saying that DBAs aim for optimization, so here's a query to help you find missing indexes that can give you information you need.  And don't forget to regularly monitor the 11 VitalSigns used by SQLRx to debug performance bottlenecks.
 
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SQL 2008  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

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For assistance or more information on optimizing your SQL Server Environment, visit us at www.sqlrx.com or email Lori Brown at lorib@isi85.com.  

Sincerely,

Lori Brown | SQLRx Senior Consultant | Integrated Services, Inc.
4144 N. Central Expwy, Suite 430  |  Dallas, TX  75204
Phone: 214.526.7680 x 113 | lorib@isi85.com 
 
 
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