9 Query Tuning Techniques | SQL Server Performance Tuning Made Easy

9 tips on SQL Server Query performance that anyone can apply right now to make your queries and your database go faster! Almost immediately!

Content

00:00 Introduction to Performance Tuning
00:32 Missing Index DMV in SQL Server
02:58 Removing Inferior Indexes
04:30 Converting Row Based to Set Based Logic
05:50 Analyse the Execution Plan
07:23 Indexing your Joins
08:02 Upgrading the Database Compatibility Level
08:48 Using an index with LIKE
10:10 SET STATISTICS TIME ON
10:50 Setting up Extended Events

Understanding Execution Plans

Execution plans can be viewed in SQL Server Management Studio (SSMS). When you write a query, you can display the estimated execution plan before running the query or the actual execution plan after execution.

This visual representation helps you understand how SQL Server processes your query, including the order of operations, index usage, join methods, and more. Some of the benefits include

1. Identifying Inefficiencies:

Execution plans highlight potential inefficiencies, such as table scans or missing indexes. A table scan occurs when SQL Server reads the entire table to find the data, which can be slow for large tables. Identifying and addressing these inefficiencies can significantly improve query performance.

2. Optimizing Index Usage:

Execution plans show how indexes are used in query execution. If an index is not used effectively, you might see operations like index scans instead of index seeks. Adjusting indexes based on this information can lead to faster data retrieval and improved performance.

3. Understanding Join Operations:

Execution plans detail the types of joins used (nested loops, hash joins, merge joins) and their impact on performance. By analyzing these joins, you can optimize them to ensure efficient data merging and reduce execution time.

Set Based Logic

Set-based logic in SQL Server is a programming approach that focuses on operating on sets of data as a whole rather than processing individual rows one at a time. This approach is fundamental to relational database management systems (RDBMS) and offers numerous benefits, especially for beginners learning SQL Server. Some of these benefits include:

1. Performance Efficiency

The most important benefit surely has to be the performance benefit right? As such, one of the most significant advantages of set-based logic is performance efficiency.

SQL Server is optimized for set-based operations, meaning it can process large volumes of data quickly and efficiently. When you use set-based queries, SQL Server can leverage advanced optimization techniques to execute operations faster than row-by-row processing. This leads to quicker query execution and better overall performance.

2. Simplified Code

Set-based logic allows for simpler and more readable SQL code. Why use 100 lines of code when 15 will do?

By focusing on operations that apply to entire sets of data, such as selecting, updating, or deleting multiple rows at once, you can write concise and clear queries. This not only makes the code easier to understand and maintain but also reduces the likelihood of errors compared to complex, iterative row-by-row operations.

3. Declarative Nature

Set-based logic is declarative, meaning you specify what you want to achieve without detailing the step-by-step process of how to do it. This high-level approach allows SQL Server's query optimizer to determine the most efficient execution plan automatically. It abstracts the complexity of data manipulation, enabling you to focus on the desired outcomes rather than the procedural steps

For more detailed information and examples on set-based logic in SQL Server, you can refer to the official Microsoft Docs on Query Basics. Found here

Extended Events

As discussed in my other tutorial, Extended Events (XEvents) in SQL Server is a powerful and flexible event-handling system designed to monitor and troubleshoot the SQL Server environment.

Unlike traditional SQL Server monitoring tools such as Profiler, XEvents offers a lightweight and scalable solution for gathering detailed information about system behavior and performance. Some benefits include:

1. Comprehensive Monitoring

Extended Events provide a comprehensive way to monitor SQL Server events. They allow you to capture a wide range of data, including query performance, system health, and application interactions. This breadth of monitoring capability helps in identifying performance bottlenecks, detecting anomalies, and understanding system behavior under different loads.

2. Ease of Use and Integration
3. Advanced Analysis Capabilities

Links

You can start with the official Microsoft Docs on Extended Events link: