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Dropping XML Indexes

The DROP INDEX (Transact-SQL)Transact-SQL statement can be used to drop existing primary or secondary XML and non-XML indexes. However, no options of DROP INDEX apply to XML indexes. If you drop the primary XML index, any secondary indexes that are present are also deleted.

The DROP syntax with TableName.IndexName is being phased out and is not supported for XML indexes.

Example: Creating and Dropping a Primary XML Index

In the following example, an XML index is created on an xml type column.

DROP TABLE T
GO
CREATE TABLE T (Col1 INT PRIMARY KEY, XmlCol XML)
GO
-- Create Primary XML index 
CREATE PRIMARY XML INDEX PIdx_T_XmlCol 
ON T(XmlCol)
GO
-- Verify the index creation. 
-- Note index type is 3 for xml indexes.
-- Note the type 3 is index on XML type.
SELECT *
FROM sys.xml_indexes
WHERE object_id = object_id('T')
AND name='PIdx_T_XmlCol' 
-- Drop the index.
DROP INDEX PIdx_T_XmlCol ON T

When a table is dropped, all the XML indexes on it are also automatically dropped. However, an XML column cannot be dropped from a table if an XML index exists on the column.

In the following example, an XML index is created on an xml type column. For more information, see Typed XML Compared to Untyped XML.

CREATE TABLE TestTable(
 Col1 int primary key, 
 Col2 xml (Production.ProductDescriptionSchemaCollection)) 
GO

Now, you can create a primary XML index on Co12.

CREATE PRIMARY XML INDEX PIdx_TestTable_Col2 
ON TestTable(Col2)
GO

Example: Creating an XML Index by Using the DROP_EXISTING Index Option

In the following example, an XML index is created on a column (XmlColx). Then, another XML index with the same name is created on a different column, (XmlColy). Because the DROP_EXISTING option is specified, the existing XML index on (XmlColx) is dropped and a new XML index on (XmlColy) is created.

DROP TABLE T
GO
CREATE TABLE T(Col1 int primary key, XmlColx xml, XmlColy xml)
GO
-- Create XML index on XmlColx.
CREATE PRIMARY XML INDEX PIdx_T_XmlCol 
ON T(XmlColx)
GO
-- Create same name XML index on XmlColy.
CREATE PRIMARY XML INDEX PIdx_T_XmlCol 
ON T(XmlColy) 
WITH (DROP_EXISTING = ON)
-- Verify the index is created on XmlColy.d.
SELECT sc.name 
FROM   sys.xml_indexes si inner join sys.index_columns sic 
ON     sic.object_id=si.object_id and sic.index_id=si.index_id
INNER  join sys.columns sc on sc.object_id=sic.object_id 
AND    sc.column_id=sic.column_id
WHERE  si.name='PIdx_T_XmlCol' 
AND    si.object_id=object_id('T')

This query returns the column name on which the specified XML index is created.