How do I know Stored Procedure is slowly running or doesn't have any performance issue?
After creating Stored Procedure, you must have a look at the Query Execution Plan. If you have Index/Table scan and also if it says that there are missing index then there is a performance issue and it is possible to fine-tune it.
Optimization Tips To Increase SQL Server Stored Procedure Performance -
1. Use stored procedures instead of heavy-duty queries.
2. Include the SET NOCOUNT ON statement into your stored procedures to stop the message indicating the number of rows affected by a Transact-SQL statement.
3. Call stored procedure using its fully qualified name.
4. Consider returning the integer value as a RETURN statement instead of an integer value as part of a recordset.
5. Don't use the prefix "sp_" in the stored procedure name if you need to create a stored procedure to run in a database other than the master database.
6. Use EXISTS() instead of COUNT().
7. Don’t use functions in the WHERE clause.
8. Use Join query instead of sub-query and co-related subquery.
9. Use the sp_executesql stored procedure instead of the EXECUTE statement.
10. Use sp_executesql stored procedure instead of temporary stored procedures.
11. If you have a very large stored procedure, try to break down this stored procedure into several sub-procedures, and call them from a controlling stored procedure.
12. Try to avoid using temporary tables inside your stored procedure.
13. Try to avoid using DDL (Data Definition Language) statements inside your stored procedure.
14. Add the WITH RECOMPILE option to the CREATE PROCEDURE statement if you know that your query will vary each time it is run from the stored procedure.
15. Use Index for required columns - Index should be created for all columns which are using Where, Group By, Order By, Top, and Distinct command.
16. Try to Avoid Correlated Queries i.e. Select Name, City, (Select Company_Name from Company where companyId=cs.CustomerId) from Customer cs
17. Try to Avoid Loops In Coding i.e. declare @int int; set @int=1; while @int<=100 begin Insert Into Tab values(@int,'Value'+@int); set @int=@int+1; end
18. Importance of Column Order in the index -If we are creating a Non-Clustered index on more than one column then we should consider the sequence of the columns. The order or position of a column in an index also plays a vital role in improving SQL query performance. An index can help to improve the SQL query performance if the criteria of the query match the columns that are left most in the index key. So we should place the most selective column at the leftmost side of a non-clustered index.
19. Try to Drop Index before Bulk Insertion of Data.
20. Use Sparse Column - Sparse column provide better performance for NULL and Zero data. If you have any columns that contain large amount numbers of NULL and Zero then prefer Sparse Column instead of default column of SQL Server. The sparse column takes lesser space than the regular column (without SPARSE clause).
21. Don't use the Index if the size of the table is very small.
22. Use View for complex queries.
23. Use Full-text Index if your query contains multiple wild card searches using LIKE(%%), then the use of the Full-text Index can increase the performance.
24. Try to avoid * and specify column names instead of using * in a SELECT statement.