Sql-server – Dropping Hypothetical Indexes

database-tuning-advisorindexsql serversql-server-2008

In the past I thought I'd deleted hypothetical indexes using either a DROP INDEX statement for clustered indexes and DROP STATISTICS statement for non-clustered indexes.

I have a database that is full of DTA remnants that I would like to cleanup; however, when I try to drop the object I always receive an error telling me that I cannot drop the object "because it does not exist or you do not have permission". I am a full sysadmin on the server so would expect to have rights to do anything.

I've tried this with both DROP STATS and DROP INDEX statements but both give me the same error.

Has anyone deleted these before and is there a trick I'm missing?

Addendum

Poking around in this, I just noticed that if I R-Click on the object, both the 'Script As' and 'DELETE' options are greyed out.

Best Answer

The hypothetical indexes created by the Index Tuning Wizard start with a name of "hind_%" and should not exist after the tuning has finished; they should all be removed. You can run the following script from the SQL Server Query Analyzer to remove any such indexes that may exist. You must log in by using an account that has either sysadmin or db_owner permissions, or is the owner of the object on which these statistics were created.

For example

DECLARE @strSQL nvarchar(1024) 
DECLARE @objid int 
DECLARE @indid tinyint 
DECLARE ITW_Stats CURSOR FOR SELECT id, indid FROM sysindexes WHERE name LIKE 'hind_%' ORDER BY name 
OPEN ITW_Stats 
FETCH NEXT FROM ITW_Stats INTO @objid, @indid 
WHILE (@@FETCH_STATUS  -1) 
BEGIN 
SELECT @strSQL = (SELECT case when INDEXPROPERTY(i.id, i.name, 'IsStatistics') = 1 then 'drop statistics [' else 'drop index [' end + OBJECT_NAME(i.id) + '].[' + i.name + ']' 
FROM sysindexes i join sysobjects o on i.id = o.id 
WHERE i.id = @objid and i.indid = @indid AND 
(INDEXPROPERTY(i.id, i.name, 'IsHypothetical') = 1 OR
(INDEXPROPERTY(i.id, i.name, 'IsStatistics') = 1 AND 
INDEXPROPERTY(i.id, i.name, 'IsAutoStatistics') = 0))) 
EXEC(@strSQL) 
FETCH NEXT FROM ITW_Stats INTO @objid, @indid
END
CLOSE ITW_Stats 
DEALLOCATE ITW_Stats

Above script is provided by Microsoft for more detail you can visit following link. http://support.microsoft.com/kb/q293177

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