Unused Index Script sql server

Performance Tuning is quite interesting and Index plays a vital role in it. A proper index can improve the performance and a bad index can hamper the performance.

Here is the script from my script bank which I use to identify unused indexes on any database.

Please note, if you should not drop all the unused indexes this script suggest. This is just for guidance. You should not create more than 5-10 indexes per table. Additionally, this script sometime does not give accurate information so use your common sense.

Any way, the scripts is good starting point. You should pay attention to User Scan, User Lookup and User Update when you are going to drop index. The generic understanding is if this values are all high and User Seek is low, the index needs tuning. The index drop script is also provided in the last column.

Click to Download Scripts

-- Unused Index Script
-- Original Author: Pinal Dave (C) 2011
SELECT TOP 25
o.name AS ObjectName
, i.name AS IndexName
, i.index_id AS IndexID
, dm_ius.user_seeks AS UserSeek
, dm_ius.user_scans AS UserScans
, dm_ius.user_lookups AS UserLookups
, dm_ius.user_updates AS UserUpdates
, p.TableRows
, 'DROP INDEX ' + QUOTENAME(i.name)
+ ' ON ' + QUOTENAME(s.name) + '.' + QUOTENAME(OBJECT_NAME(dm_ius.OBJECT_ID)) AS 'drop statement'
FROM sys.dm_db_index_usage_stats dm_ius
INNER JOIN sys.indexes i ON i.index_id = dm_ius.index_id AND dm_ius.OBJECT_ID = i.OBJECT_ID
INNER JOIN sys.objects o ON dm_ius.OBJECT_ID = o.OBJECT_ID
INNER JOIN sys.schemas s ON o.schema_id = s.schema_id
INNER JOIN (SELECT SUM(p.rows) TableRows, p.index_id, p.OBJECT_ID
FROM sys.partitions p GROUP BY p.index_id, p.OBJECT_ID) p
ON p.index_id = dm_ius.index_id AND dm_ius.OBJECT_ID = p.OBJECT_ID
WHERE OBJECTPROPERTY(dm_ius.OBJECT_ID,'IsUserTable') = 1
AND dm_ius.database_id = DB_ID()
AND i.type_desc = 'nonclustered'
AND i.is_primary_key = 0
AND i.is_unique_constraint = 0
ORDER BY (dm_ius.user_seeks + dm_ius.user_scans + dm_ius.user_lookups) ASC
GO

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That’s a great script (as yours always are), however I think you are missing another class of “missing indexes”, and that is indexes that don’t have stats at all. Rows are only written to dm_db_index_usage_stats when an index is used. If that index is totally un-used (even for writing to), it won’t appear in dm_db_index_usage_stats and therefore won’t be included in your script.
Try this on a production system, you might be surprised by how many rows it returns:


SELECT object_name(i.object_id) as tableName, i.name as indexName
FROM sys.indexes i
LEFT JOIN sys.dm_db_index_usage_stats s ON i.object_id = s.object_id AND i.index_id = s.index_id AND s.database_id = db_id()
WHERE objectproperty(i.object_id,’IsUserTable’) = 1 and i.index_id> 0
AND s.object_id IS NULL
AND i.is_Primary_Key = 0
AND i.is_unique_constraint = 0
AND i.is_unique = 0