Beyond SET NOCOUNT ON: Exploring Alternative Techniques for Peak SQL Server Performance

• Controls how the number of affected rows by a T-SQL statement is displayed.
• By default (SET NOCOUNT OFF), SQL Server shows this count in the messages window after executing the statement.
• With SET NOCOUNT ON, this message is suppressed.

Benefits of using SET NOCOUNT ON:

• Improved Performance: This is especially helpful in stored procedures that:
  • Execute many statements that don't return data (like DDL or DML operations).
  • Utilize T-SQL loops for bulk operations.
• Suppressing the row count message reduces network traffic between the SQL Server and the client application. This can lead to faster execution, particularly for remote connections.

Things to Consider:

• SET NOCOUNT ON only affects the current execution. It's not a global setting.
• It doesn't prevent the @@ROWCOUNT system function from working. You can still use @@ROWCOUNT to retrieve the number of affected rows even when SET NOCOUNT is ON.

Common Use Case:

Placing SET NOCOUNT ON at the beginning of a stored procedure is a frequent practice to optimize its performance, especially for those with many data manipulation statements.

Example:

SET NOCOUNT ON;

UPDATE Customers SET City = 'New York' WHERE Country = 'USA';

-- Do something else...

SET NOCOUNT ON;

UPDATE Customers SET City = 'London' WHERE Country = 'UK';

-- This line won't be displayed: (10 rows affected)

This suppresses the message about the number of rows affected by the UPDATE statement.

Stored Procedure with Multiple Statements:

CREATE PROCEDURE UpdateCustomerCity (
  @country nvarchar(50),
  @newCity nvarchar(50)
)
AS
BEGIN
  SET NOCOUNT ON;

  UPDATE Customers SET City = @newCity WHERE Country = @country;

  -- Additional logic here (e.g., logging)
END;

Here, SET NOCOUNT ON improves performance for the entire stored procedure execution.

T-SQL Loop with SET NOCOUNT ON:

SET NOCOUNT ON;

DECLARE @i int;

SET @i = 1;

WHILE @i <= 100
BEGIN
  -- Update a single row in a loop (replace with your actual logic)
  UPDATE Products SET Price = Price * 1.1 WHERE ProductID = @i;
  SET @i = @i + 1;
END;

This approach helps optimize performance in loops that execute many data manipulation statements.

Remember:

• Use SET NOCOUNT ON judiciously. If your application relies on the row count information, keep it turned off.
• Consider alternative performance optimization techniques for complex scenarios.

• Focus on selecting only the necessary columns in your queries. Avoid using SELECT * as it retrieves all columns, even if you don't use them.
• Utilize appropriate WHERE clauses to filter data efficiently and reduce the number of rows processed.

Use appropriate data types:

• Ensure columns hold data in the most efficient data type possible. For example, use INT for whole numbers instead of VARCHAR.
• Utilize indexes on frequently used columns in WHERE clause conditions for faster retrieval.

Stored procedure optimization:

• Break down complex stored procedures into smaller, more manageable ones.
• Avoid unnecessary cursor usage. Cursors can be resource-intensive. Consider set-based operations instead when possible.

Query Tuning Techniques:

• Analyze query plans to identify bottlenecks and optimize queries accordingly.
• Utilize tools like SQL Server Profiler to monitor query execution and identify slow queries

Hardware and software optimization:

• Ensure sufficient RAM and CPU resources are allocated to SQL Server for smooth operation.
• Consider using partitioned tables for large datasets to improve query performance.