Reporting Services Unicode Parameters Cause Performance Issues

Question

When I create a report using string parameters,  reporting services sends the SQL to SQL Server with an N prefix on the string parameters.  This is the behavior even when the underlying data table has no unicode datatypes.  This causes SQL Server to do a scan instead of a seek on these queries.  Can this behavior be modified to send the parameters as non-unicode text?

Answer 1

Work around to overcome SSRS report performance due to UNICODE conversion issue:
I have used a new parameter (of type Internal) which collects/duplicates the original parameter values as comma separated in string.
In the report Dataset query, parse the comma separated string into  a list into a vairable table using XML trick.
Use the variable table in WHERE IN clause
Steps:
Create a new Internal parameter (call it InternalParameter1)
Under Default Values -> Specify values : Add Exp : =join( Parameters!OrigParameter1.Value,",")
Pass/Use the InternalParameter1 in your dataset query.
Example code
DECLARE @InternalParameter1 NVARCHAR(MAX)
SET @InternalParameter1 = '100167600,
100167601,
4302853605,
4030753556,
4026938411
--- Load comma separated string to a temp variable table ---
SET ARITHABORT ON
DECLARE @T1 AS TABLE (PARALIST VARCHAR(100))
INSERT @T1 SELECT Split.a.value('.', 'VARCHAR(100)') AS CVS FROM
( SELECT CAST ('<M>' + REPLACE(@InternalParameter1, ',', '</M><M>') + '</M>' AS XML) AS CVS ) AS A CROSS APPLY CVS.nodes ('/M') AS Split(a)
--- Report Dataset query ---
SELECT CONTRACT_NO, report fields… FROM mytable
WHERE CONTRACT_NO IN (SELECT PARALIST FROM @T1) -- Use temp variable table in where clause
Mahesh