1. Stored Procedure Optimization Preventing SP Time Out Delay Deadlocking More DiskReads By: Nix

2. CREATE PROCEDURE [dbo].[pr_get_user_ids] ( @in_SetupId int ) As begin Declare @local_SetupId int =@in_SetupId Select UserId from UserDetail where SetupId=@local_SetupId end Parameter Sniffing This is the most common problem, The workaround is to declare the input params again with different variable name and use the new variable through out the SP. In the Example @local_SetupId In short, parameter sniffing is one exec plan for all parameter combinations. - This option causes the compilation process to ignore the value for the specified variable and use the specified value instead. - Unlike the other workaround (Option(Recompile)), this option avoid the overhead of recompiling the query every time.

3. Use Local Temp Tables Store the data from large tables such as Product / Customer/ ProductHierarchy into Local temp Tables and Use them when joining – This is will Prevent the joining of heavy tables. SELECT * into #TempProductHierarchy FROM (SELECT ProductHierarchy,ProductHierarchyId,ProductId from ProductHierarchyDetails where SetupId=@local_SetupId ) AS TPH SELECT ProductCodeInterface from masters.Product P inner join #tempProductHierarchy on P.ProductId=#TempProductHierarchy.ProductId Instead of SELECT ProductCodeInterface from masters.Product P inner join masters.ProductHierarchyDetail PHD on P.ProductId=PHD.ProductId where P.SetupId=@local_SetupId Select only the needed columns for your Transaction operation and put it into a local temp table. Hence on performing joins the tables will be lighter and preventing the use of excess Resource. In the Example We have filtered out few columns from ProductHierarchy table using setupid in where clause and used it to join with Product table. This is Subject to temp Db Size. Consider the temp Db size.

4. SELECT * into #TempProductHierarchy FROM (SELECT ProductHierarchy,ProductHierarchyId,ProductId from ProductHierarchyDetails where SetupId=@local_SetupId ) AS TPH Create NonClustered Index IDX_TP4 On #TempProductHierarchy(ProductId) Use NON Clustered Index Use Non Clustered Index on temp tables for quicker Execution Once you have created a temp table, set index on the primary key of the table – on which you will be performing the join operation. In the example we have read the Product Hierarchy table into a temp table and we have created a non- clustered index onto the primary key i.e ProductId

5. Select * from ProductHierarchy WITH(NOLOCK) Use With(NOLOCK) NOLOCK typically (depending on your DB engine) means give me your data, and I don't care what state it is in, and don't bother holding it still while you read from it. It is all at once faster, less resource-intensive Use NOLOCK on master tables and not everywhere. Using NoLock may become dangerous sometimes, so check the query exec plan when in doubt.

6. Instead Of SELECT * from trans.Promotion P inner join masters.Product PP with(NOLOCK) on PP.SetupId=P.SetupId inner join masters.Customer CC with(NOLOCK) on CC.SetupId=P.SetupId Where PP.SetupId=@local_SetupId SELECT * from trans.Promotion P inner join masters.Product PP with(NOLOCK) on PP.SetupId=@local_SetupId inner join masters.Customer CC with(NOLOCK) on CC.SetupId=@local_SetupId Join On the InputParameter This will reduce the operation size and the disk read Join on input parameter instead of filtering in where condition. As you can see here we have joined on setupid i.e the input parameter instead of joining on the setupid of the other table and then filtering in where condition.

7. Dont use "SELECT *" in a SQL query Prevent the use of “Select *” Causes Indexing issues and Binding issues

8. SELECT PromotionId,AmendVersion FROM trans.Promotion WHERE EXISTS (SELECT top 1 PromotionId FROM trans.PromotionExtract WHERE Promotion.SetupId=1099) Use EXISTS To check if any data exists in a particular table, use EXISTS instead of relying on Count its more effective.

9. SELECT * into #TempProduct FROM(SELECT ProductId,LevelId,ProductCodeInterface,Name from Product where SetupId=@local_SetupId and IsActive=1) AS TP Use Local Temp Tables (#TempTableName) Prevent using Global hash tables (##)

10. Declare @sampleString varchar(max) = 'nevermind the promotions' Declare @sizeOfString int set @sizeOfString= len(@sampleString) SELECT @sizeOfString Use Local Variables to Store the FunctionCall return Prevent calling the string functions or date functions Over and over again, instead store ‘em in local variables if you are going to reuse the value.

11. BEGIN TRY -- Logic / Query here END TRY BEGIN CATCH ----------------------------------------------------------------------- DECLARE @ErrMsg VARCHAR(255) -- Error Message,@ErrNo INT -- Error Number,@ErrSeverity INT -- Error Severity,@ErrProc VARCHAR(255) -- Error Procedure,@ErrLine INT -- Error Line SELECT @ErrMsg = ERROR_MESSAGE(),@ErrNo = ERROR_NUMBER(),@ErrSeverity = 17,@ErrProc = ERROR_PROCEDURE(),@ErrLine = ERROR_LINE() RAISERROR ( @ErrMsg,@ErrSeverity,1,@ErrNo,@ErrLine,@ErrProc ) ----------------------------------------------------------------------- END CATCH END Use Try - Catch

12. SET NOCOUNT ON Select PromotionId from Promotion Use SET NOCOUNT ON Whenever we write any procedure and execute it a message appears in message window that shows number of rows affected with the statement written in the procedure. When SET NOCOUNT is ON, the count is not returned.

13. Do not try to use DDL statements inside a stored procedure that will reduces the chance to reuse the execution plan. DDL statements like CREATE,ALTER,DROP,TRUNCATE etc. Prevent Usage of DDL Statements

14. Use Alias --Wrong Statement SELECT PromotionId, P.VersionedPromotionId, Name, PIE.InvestmentTypeId from Promotion P Inner join PromotionInvestment PIE on PIE.VersionedPromotionId=P.VersionedPromotionId where P.Name='Blah' --Correct Statement SELECT P.PromotionId, P.VersionedPromotionId, P.Name, PIE.InvestmentTypeId from Promotion P Inner join PromotionInvestment PIE on PIE.VersionedPromotionId=P.VersionedPromotionId where P.Name='Blah' If an alias is not present, the engine must resolve which tables own the specified columns. A short alias is parsed more quickly than a long table name or alias. If possible, reduce the alias to a single letter

15. Don't use UPDATE instead of CASE Take this scenario, for instance: You're inserting data into a temp table and need it to display a certain value if another value exists. Maybe you're pulling from the Customer table and you want anyone with more than $100,000 in orders to be labeled as "Preferred." Thus, you insert the data into the table and run an UPDATE statement to set the CustomerRank column to "Preferred" for anyone who has more than $100,000 in orders. The problem is that the UPDATE statement is logged, which means it has to write twice for every single write to the table. The way around this, of course, is to use an inline CASE statement in the SQL query itself. This tests every row for the order amount condition and sets the "Preferred" label before it's written to the table.

16. Avoid Functions on RHS Don’t use thisselect * from Promotion where YEAR(StartDate) = 2015 and MONTH(StartDate) = 6 Instead use thisSelect * From Promotion Where StartDate between '6/1/2015' and '6/30/2015'

17. Specify optimizer hints in SELECT most cases the query optimizer will pick the appropriate index for a particular table based on statistics, sometimes it is better to specify the index name in your SELECT query. Do not use this unless you know what you are doing. SELECT * FROM Promotion WITH ( Index(IdxPromotionId)) WHERE Name = 'blah' and Setupid=1099