Question

After query optimization I got results that are ok and I wanted to alter stored procedure, but got much worst results after SP execution, than it was after query execution!

Firstly, I think at number of reads. What can be reason for so different results?

Query is identical like in SP, only difference is that in query I declared parameter, but in SP that was input parameter. Value that is set to parameter is also same. To avoid ‘recorded data’ first I recompiled SP and after that done DROP and CREATE, but results were also much different.

Query is like this (table and column names are changed because of simplification, and number of columns is reduced):

DECLARE @Var1 varchar(20)    
SET @Var1 = @Var1 + '%'       

DECLARE @Var2 TIMESTAMP    
SELECT @Var2 = CONVERT(TIMESTAMP, ID, 0)    
FROM    
 X_TIMESTAMPS (NOLOCK)    
WHERE    
 TABLE = 'T1'     


declare @Var3 varbinary(8)    
SELECT @Var3 = max(IdTimeStamps)    
FROM    
 T1 (NOLOCK)     

SELECT o.c1  
  , o.c2   
  , o.c3    
  , v.c4    
  , v.c5   
  , p.c6    
  , p.c7    
  , va.c8    
  , isnull(s.c9, '') AS c9    
  , CASE o.c10    
     WHEN 1 THEN    
      0    
     ELSE    
      1    
    END c10   
  , o.c11    
FROM    
 T1 o (NOLOCK)    
 JOIN T2 p (NOLOCK)    
  ON o.c1 = p.c12    
 JOIN T3 i (NOLOCK)    
  ON (o.c13 = i.c14)    
 JOIN T4 v (NOLOCK)    
  ON (v.c4 = i.c15)    
 LEFT JOIN T5 s (NOLOCK)    
  ON (o.c16 = s.c17)    
 JOIN T6 va (NOLOCK)    
  ON o.c11 = va.c18    
WHERE    
 o.c1 LIKE @Var1    
 AND o.c2 > @Var2 

And procedure is like this:

CREATE PROCEDURE [dbo].[SP1] @Var1 varchar(20) ='' 
WITH RECOMPILE  
AS        
BEGIN

    PREVIOUS QUERY WITHOUT DECLARATION FOR @Var1

END

TnX in advance!

Nemanja

Answer 1

It’s because different execution plans are used for query with constants and sp with parameeters. You can try a few tricks

Create inline table function and try it

create function sf_test
(
    @param1 int
)
returns table
as
return
    your query using @in_param1

or

declare additional parameters in your procedure like this

create procedure sp_test
(
    @param1 int
)
as
begin
    declare @in_param1 int

    select @in_param1 = @param1

    your query using @in_param1
end

you can also try using option with recompile in your procedure, or use dynamic SQL