Gokul's Blog

Sql Server Tuning & suggest missing Indexes Query

2 Comments

I came across this great article on SQL server performance & tuning.

Main Page: http://use-the-index-luke.com/. As the author explains in the preface

As it turns out, the only thing developers need to know to write efficient SQL is how indexes work.

Some interesting topics which will help us to fine tune Sql code:

One of my friend(Doug) suggested about this nice little piece of code thought would add here for easy reference.

/* ------------------------------------------------------------------
-- Title:   FindMissingIndexes
-- Author:  Brent Ozar
-- Date:    2009-04-01
-- Modified By: Clayton Kramer <ckramer.kramer @="" gmail.com="">
-- Description: This query returns indexes that SQL Server 2005
-- (and higher) thinks are missing since the last restart. The
-- "Impact" column is relative to the time of last restart and how
-- bad SQL Server needs the index. 10 million+ is high.
-- Changes: Updated to expose full table name. This makes it easier
-- to identify which database needs an index. Modified the
-- CreateIndexStatement to use the full table path and include the
-- equality/inequality columns for easier identifcation.
------------------------------------------------------------------ */
SELECT
      [Impact] = (avg_total_user_cost * avg_user_impact) * (user_seeks + user_scans),
      [Table] = [statement],
      [CreateIndexStatement] = 'CREATE NONCLUSTERED INDEX ix_'
            + sys.objects.name COLLATE DATABASE_DEFAULT
            + '_'
            + REPLACE(REPLACE(REPLACE(ISNULL(mid.equality_columns,'')+ISNULL(mid.inequality_columns,''), '[', ''), ']',''), ', ','_')
            + ' ON '
            + [statement]
            + ' ( ' + IsNull(mid.equality_columns, '')
            + CASE WHEN mid.inequality_columns IS NULL THEN '' ELSE
                  CASE WHEN mid.equality_columns IS NULL THEN '' ELSE ',' END
            + mid.inequality_columns END + ' ) '
            + CASE WHEN mid.included_columns IS NULL THEN '' ELSE 'INCLUDE (' + mid.included_columns + ')' END
            + ';',
      mid.equality_columns,
      mid.inequality_columns,
      mid.included_columns
FROM sys.dm_db_missing_index_group_stats AS migs
      INNER JOIN sys.dm_db_missing_index_groups AS mig ON migs.group_handle = mig.index_group_handle
      INNER JOIN sys.dm_db_missing_index_details AS mid ON mig.index_handle = mid.index_handle
      INNER JOIN sys.objects WITH (nolock) ON mid.OBJECT_ID = sys.objects.OBJECT_ID
WHERE (migs.group_handle IN
            (SELECT TOP (500) group_handle
            FROM sys.dm_db_missing_index_group_stats WITH (nolock)
            ORDER BY (avg_total_user_cost * avg_user_impact) * (user_seeks + user_scans) DESC))
      AND OBJECTPROPERTY(sys.objects.OBJECT_ID, 'isusertable') = 1
ORDER BY [Impact] DESC , [CreateIndexStatement] DESC
Advertisements

2 thoughts on “Sql Server Tuning & suggest missing Indexes Query

  1. Some related information to the script you’ve posted , and is useful in understanding the sys.dm_db_missing_index_details dmv . Check:
    http://www.sqlserver-dba.com/2011/07/-missing-indexes-equality-and-inequality-on-sysdm_db_missing_index_details.html

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s