Speeding up a query on a concatenated field.

Question

Hi,
I have a view with a concatenated field that basically comes down on this:
ALTER VIEW [dbo].[_FO_QP_Items_4_0] AS
SELECT
Col A ,Col B --etc
,CONVERT(nvarchar(36), sysguid) +'|'+crdnr AS [LevCode]
FROM table A
As you see I am concatenating 2 fields together to get a unique [LevCode] (concatenating Itemcode + Supplier code)
If I query that view like this, it runs rather slow on a 500.000+ rows table:
SELECT *
FROM [dbo].[_FO_QP_Items_4_0]
WHERE [LevCode] = 'DF007704-38EF-4389-8544-E70CC32404D5| 60102'
ORDER BY Col A
Unfortunately I am not able to add an extra column to the table and concatenate the fields there. 
Is there a way to speed up the query (or view).
Thanks for helping me out here.

Answer 1

Index view has high overhead. It has to be really justified.
BOL: "Indexed views work best when the underlying data is infrequently updated. The maintenance of an indexed view can be greater than the cost of maintaining a table index. If the underlying data is updated frequently, the cost of maintaining the indexed
view data may outweigh the performance benefits of using the indexed view. If the underlying data is updated periodically in batches but treated primarily as read-only between updates, consider dropping any indexed views before updating, and rebuilding them
afterward. Doing this may improve performance of the updates."
Reference:
https://technet.microsoft.com/en-us/library/ms187864%28v=sql.105%29.aspx?f=255&MSPPError=-2147217396
Kalman Toth Database & OLAP Architect
SQL Server 2014 Database Design
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