SQL Server 2022 has ushered in a new era of database optimization, thanks to the remarkable advancements in Intelligent Query Processing (IQP). These enhancements are designed to automatically improve the performance of queries, making it easier to manage and optimize databases without extensive manual intervention. In this blog, we will delve into the latest IQP features, providing detailed explanations, examples, and code snippets to demonstrate their impact on query performance. Let’s explore these game-changing features! 🌟

1. Parameter Sensitive Plan Optimization (PSPO) 🔄

One of the common challenges in SQL Server query performance is parameter sniffing, where the query optimizer generates an execution plan based on the first parameter value it encounters. This can lead to suboptimal plans for subsequent executions with different parameter values. SQL Server 2022 introduces Parameter Sensitive Plan Optimization (PSPO) to address this issue.

How PSPO Works: PSPO allows SQL Server to create multiple execution plans for a single query, each tailored to different parameter values. This ensures that the most efficient plan is used for each specific scenario.

Example:

Consider the following query that retrieves orders based on CustomerID:

SELECT OrderID, OrderDate, TotalAmount
FROM Orders
WHERE CustomerID = @CustomerID;

Without PSPO, SQL Server might create a plan optimized for a specific CustomerID, potentially causing poor performance for other customers with different data distributions. With PSPO, SQL Server can store multiple plans, ensuring optimal performance across different parameter values.

2. Degree of Parallelism Feedback (DOP Feedback) 🔢

The Degree of Parallelism (DOP) determines how many threads SQL Server uses to execute a query. Incorrect DOP settings can lead to inefficient CPU usage and poor query performance. SQL Server 2022 introduces DOP Feedback, which dynamically adjusts the DOP based on actual runtime conditions.

How DOP Feedback Works: DOP Feedback monitors the performance of parallel queries and adjusts the DOP for subsequent executions, aiming to find the most efficient level of parallelism.

Example:

SELECT ProductID, SUM(Quantity) AS TotalQuantity
FROM Sales
GROUP BY ProductID;

For a query like this, SQL Server may initially choose a DOP based on its estimates. If the initial DOP is too high or too low, resulting in suboptimal performance, DOP Feedback will adjust it in future executions, optimizing both CPU utilization and query execution time.

3. Memory Grant Feedback (Persisted) 🧠

Memory Grant Feedback was first introduced in SQL Server 2017 to adjust memory grants dynamically based on actual execution requirements. SQL Server 2022 enhances this feature with persistence, meaning the adjustments are retained across query executions, even if the server restarts.

How Memory Grant Feedback (Persisted) Works: If a query is granted too much or too little memory, it can lead to resource contention or wasted resources. The persisted Memory Grant Feedback feature adjusts the memory grant size based on the query’s actual memory usage.

Example:

SELECT CustomerID, COUNT(*) AS OrderCount
FROM Orders
GROUP BY CustomerID;

If this query initially receives a larger memory grant than necessary, it may lead to wasted resources. Memory Grant Feedback will reduce the grant for future executions, improving resource utilization.

4. Query Store Hints 🎯

Query Store Hints provide a mechanism to apply hints to specific queries without modifying the source code. This feature is particularly useful for optimizing third-party applications or legacy code where you cannot directly alter the SQL statements.

How Query Store Hints Work: You can use Query Store Hints to influence the optimizer’s choices, such as forcing the use of a specific index or join type, without changing the application code.

Example:

Imagine you have a query that benefits from using a specific index:

SELECT * FROM Products
WHERE ProductName = 'Gadget';

You can apply a hint to force the use of a particular index:

EXEC sp_query_store_set_hints @query_id = 1, @hints = 'OPTION (FORCESEEK)';

This ensures that the query optimizer selects the most efficient execution plan, improving query performance.

5. Intelligent Query Processing (IQP) Mode 🚀

The IQP mode in SQL Server 2022 includes several key features that collectively enhance query performance. By enabling IQP mode, you automatically gain access to a suite of optimizations, including Adaptive Joins, Batch Mode on Rowstore, and more.

Key Features in IQP Mode:

• Adaptive Joins: Dynamically choose between different join strategies based on runtime conditions.
• Batch Mode on Rowstore: Use batch processing for rowstore data, significantly improving performance for certain workloads.
• Approximate Query Processing: Speed up queries with approximate results where absolute precision is not required.

Enabling IQP Mode:

To enable IQP mode, use the following T-SQL commands:

ALTER DATABASE [YourDatabaseName] SET QUERY_STORE = ON;
ALTER DATABASE SCOPED CONFIGURATION SET LEGACY_CARDINALITY_ESTIMATION = OFF;
ALTER DATABASE SCOPED CONFIGURATION SET INTERLEAVED_EXECUTION_TVF = ON;
ALTER DATABASE SCOPED CONFIGURATION SET BATCH_MODE_ADAPTIVE_JOINS = ON;
ALTER DATABASE SCOPED CONFIGURATION SET BATCH_MODE_ON_ROWSTORE = ON;

This configuration ensures that your database leverages the latest IQP features, providing significant performance improvements for complex queries.

Conclusion 🎉

SQL Server 2022’s Intelligent Query Processing enhancements represent a significant leap forward in database performance optimization. Whether dealing with parameter-sensitive queries, complex joins, or memory-intensive operations, these features provide automated, data-driven solutions that enhance efficiency and performance.

By adopting these advancements, you can ensure that your SQL Server environment operates at peak performance, with minimal manual intervention. Explore these features in your SQL Server 2022 deployment and experience the transformative impact of Intelligent Query Processing! 🚀✨

For more tutorials and tips on SQL Server, including performance tuning and database management, be sure to check out our JBSWiki YouTube channel.

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.