Thursday 9 July 2009

Generate Index scripts using included columns

This article is a continuation of the previous article http://samsudeenb.blogspot.com/2007/11/scripts-to-drop-and-recreate-indexes-in.html with small enhancement to generate the index scripts with included columns. The below function “fGetIncludedIndex is used to get the included columns for a given index.

CREATE FUNCTION fGetIncludedIndex (
@objname VARCHAR(50),
@indid INT
)
RETURNS NVARCHAR(200)
AS
BEGIN
DECLARE @V_IncludedCol NVARCHAR(200)
select @V_IncludedCol = COALESCE(@V_IncludedCol + ',', '') +
( select name from sys.syscolumns where id =a.Object_id and colid =a.column_id)
from sys.index_columns a
where object_name(a.object_id) =@objname
and a.index_id =@indid
and a.Is_included_column =1
order by a.index_column_id
return @V_IncludedCol
END


After creating the function in the DB make a small change to the existing query( highlighted in bold) to generate the index scripts with included columns

SELECT 'CREATE ' +
CASE IS_UNIQUE WHEN 1 THEN 'UNIQUE ' ELSE ' ' END +
'NONCLUSTERED ' + ' INDEX '+
NAME + ' ' +' ON ' +
OBJECT_NAME (OBJECT_ID) +
'('+
DBO.fGetIndexCols (object_NAME(OBJECT_ID), index_id) + ')'
+Case when dbo.fGetIncludedIndex(object_NAME(OBJECT_ID), index_id) is null then '' else ' INCLUDE ('+dbo.fGetIncludedIndex(object_NAME(OBJECT_ID), index_id)+')' end +
' ON ['+
( SELECT GROUPNAME
FROM SYSFILEGROUPS
WHERE GROUPID = DATA_SPACE_ID
) + ']' IndexScript
FROM SYS.INDEXES
WHERE NAME IS NOT NULL
AND Is_Primary_Key =0
AND type_desc ='NONCLUSTERED'
AND OBJECT_ID > 97

17 comments:

Nikolaj Henrichsen said...

This code rocks!
Thank you - you made my day.

Randhir said...

Great!!!!!!!!!!
Thanx..........

Randhir said...

Great..........

Thanx

Anonymous said...

Thanks for this! Improved it a bit (I think) by giving it the capability of determining schema.
SELECT 'CREATE ' +
CASE IS_UNIQUE WHEN 1 THEN 'UNIQUE ' ELSE ' ' END +
'NONCLUSTERED ' + ' INDEX '+
c.name + ' ' +' ON ' + '[' + a.name + ']' + '.' + '[' + b.name + ']' +
'('+
DBO.fGetIndexCols (b.name, index_id) + ')'
+Case when dbo.fGetIncludedIndex(b.name, index_id) is null then '' else ' INCLUDE ('+dbo.fGetIncludedIndex(b.name, index_id)+')' end +
' ON ['+
( SELECT GROUPNAME
FROM SYSFILEGROUPS
WHERE GROUPID = DATA_SPACE_ID
) + ']' + char(10) + 'GO' IndexScript
FROM
sys.schemas a JOIN sys.objects b ON
a.schema_id = b.schema_id JOIN sys.indexes c ON
(b.object_id = c.object_id)
WHERE
c.NAME IS NOT NULL
AND c.Is_Primary_Key =0
AND c.type_desc ='NONCLUSTERED'
AND c.object_id > 97
AND b.type = 'U'
ORDER BY
a.name,b.name

--Then Generate statement to DROP INDEXES

SELECT
'DROP INDEX ' + '[' + a.name + ']' + '.' + '[' + b.name +']' + '.'+ '[' + c.name + ']' + CHAR(10) + 'GO'
FROM
sys.schemas a JOIN sys.objects b ON
a.schema_id = b.schema_id JOIN sys.indexes c ON
(b.object_id = c.object_id)
WHERE
c.NAME IS NOT NULL
AND c.Is_Primary_Key =0
AND c.type_desc ='NONCLUSTERED'
AND c.object_id > 97
AND b.type = 'U'
ORDER BY
a.name,b.name

Samsudeen B said...

Thanks Stephen

Jack said...

Great Code. I have also stuck in such kind of code. This is one of the most common error in SQL Server Database. I read many blog posts, forums & articles about this error. In many cases, the solution that you provided is not surely resolve this error.
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Unknown said...

Many thanks for samsudeenb & stephen for the above scripts. I encountered some problems when I ran them (on SQL Sever 2016, now in April 2018):
1. I have indexes with many columns and includes that end up running out of space in the UDFs (so I changed some variables to NVARCHAR(MAX)
2. I have Unique Constraints that end up becoming unique indexes in both the drop & create scripts (so I changed to ALTER TABLE x ADD/DROP CONSTRAINT ...)
3. I ran into trouble executing the drop & create scripts due to the batch separator GO, so I changed it to ";"
4. For descending columns, "(-)" caused troubles, so I changed to " DESC"

(NB: due to blogger.com's 4096 bytes restriction, I have to break the code into 2 parts)
In the interest of sharing, here are my modified scripts. Kindly advise if there are areas I should improve on...

-- *1. fGetIndexCols
CREATE FUNCTION [dbo].[fGetIndexCols]
(
@objname VARCHAR(50),
@indid INT
)
RETURNS NVARCHAR(MAX)
AS
BEGIN

DECLARE @keys NVARCHAR(MAX)
DECLARE @i int, @thiskey NVARCHAR(131), @objid BIGINT

SELECT @objid = object_id(@objname)
SELECT @keys = index_col(@objname, @indid, 1), @i = 2

IF (indexkey_property(@objid, @indid, 1, 'isdescending') = 1)
SELECT @keys = @keys + ' DESC'
SELECT @thiskey = index_col(@objname, @indid, @i)
IF ((@thiskey is not null) and (indexkey_property(@objid, @indid, @i, 'isdescending') = 1))
SELECT @thiskey = @thiskey + ' DESC'

WHILE (@thiskey is not null )
BEGIN

SELECT @keys = @keys + ', ' + @thiskey, @i = @i + 1
SELECT @thiskey = index_col(@objname, @indid, @i)
IF ((@thiskey is not null) and (indexkey_property(@objid, @indid, @i, 'isdescending') = 1))
SELECT @thiskey = @thiskey + ' DESC'
END

RETURN (@KEYS)
END

-- *2. fGetIncludedIndex
CREATE FUNCTION [dbo].[fGetIncludedIndex] (
@objname VARCHAR(50),
@indid INT
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
DECLARE @V_IncludedCol NVARCHAR(MAX)
select @V_IncludedCol = COALESCE(@V_IncludedCol + ',', '') +
( select name from sys.syscolumns where id =a.Object_id and colid =a.column_id)
from sys.index_columns a
where object_name(a.object_id) =@objname
and a.index_id =@indid
and a.Is_included_column =1
order by a.index_column_id
return @V_IncludedCol
END

-- Create/Drop scripts to follow as a separate comment

Unknown said...

-- Follow on to earlier comment, here's the drop/add scripts

-- *3. Generate CREATE INDEX/CONSTRAINT statements
SELECT
CASE
WHEN is_unique_constraint = 1 -- For Unique Constraint
THEN 'ALTER TABLE '
+ '[' + a.name + ']' + '.' + '[' + b.name + ']'
+ ' ADD CONSTRAINT '
+ c.name + ' UNIQUE ('
+ DBO.fGetIndexCols (b.name, index_id) + ') '
ELSE 'CREATE ' -- For Non-Clustered Indexes
+ CASE IS_UNIQUE WHEN 1 THEN 'UNIQUE ' ELSE '' END -- Was ELSE ' '
+ 'NONCLUSTERED INDEX '
+ c.name + ' '
+ ' ON ' + '[' + a.name + ']' + '.' + '[' + b.name + '] ('
+ DBO.fGetIndexCols (b.name, index_id) + ')'
+ CASE
WHEN dbo.fGetIncludedIndex(b.name, index_id) IS NULL THEN ''
ELSE ' INCLUDE (' + dbo.fGetIncludedIndex(b.name, index_id) + ') ' END
END
+ 'ON ['
+ ( SELECT GROUPNAME FROM SYSFILEGROUPS WHERE GROUPID = DATA_SPACE_ID)
+ ']' + ';' -- Was + ']' + char(10) + 'GO'
AS
IndexScript
FROM
sys.schemas a
JOIN
sys.objects b ON a.schema_id = b.schema_id
JOIN
sys.indexes c ON (b.object_id = c.object_id)
WHERE
c.NAME IS NOT NULL
AND c.Is_Primary_Key =0
AND c.type_desc ='NONCLUSTERED'
AND c.object_id > 98 -- Was 97; however, changing it to 98 did not make a difference to output
AND b.type = 'U'
ORDER BY
c.is_unique_constraint, a.name, b.name -- Was a.name,b.name
;


-- *4. Generate DROP INDEX statements
SELECT
CASE WHEN is_unique_constraint = 1
THEN 'ALTER TABLE ' + '[' + a.name + ']' + '.' + '[' + b.name +']' + ' DROP CONSTRAINT ' + '[' + c.name + ']'
ELSE 'DROP INDEX ' + '[' + a.name + ']' + '.' + '[' + b.name +']' + '.'+ '[' + c.name + ']'
END
+ ';' -- Was + CHAR(10) + 'GO'
FROM
sys.schemas a
JOIN
sys.objects b ON a.schema_id = b.schema_id
JOIN
sys.indexes c ON (b.object_id = c.object_id)
WHERE
c.NAME IS NOT NULL
AND c.Is_Primary_Key = 0
AND c.type_desc ='NONCLUSTERED'
AND c.object_id > 98 -- Was 97
AND b.type = 'U'
ORDER BY
c.is_unique_constraint, a.name, b.name -- Was a.name,b.name
;