SQL Server’s Query Store provides a handy way to track query performance over time, making it easier to troubleshoot issues and optimize workloads. To get the most out of it, it helps to understand the various configuration options that control how it collects, stores, and manages data.
Query Store
How to Disable Query Store in SQL Server
Query Store captures query execution history, plans, and runtime statistics over time. If you need to stop this data collection (whether to reduce overhead, troubleshoot issues, or prepare for maintenance) you can disable Query Store on a per-database basis.
What is a Query Plan Cache?
A query plan cache is an area of a database management system‘s memory that stores compiled execution plans for queries. When you execute a query, the database’s optimizer analyzes the query and creates an execution plan, which is basically a set of instructions for how to retrieve and process the requested data.
But compiling this plan requires computational resources, so database systems cache it in memory for reuse rather than recompiling the same plan repeatedly.
This caching mechanism is a fundamental performance optimization found in virtually all modern relational database systems. By reusing compiled plans, databases avoid the overhead of repeatedly analyzing the same queries, resulting in faster query execution and reduced CPU consumption.
How to Check Query Wait Statistics in SQL Server’s Query Store (T-SQL)
SQL Server’s Query Store can capture wait statistics that show what queries are waiting on during execution. This includes things like locks, I/O, CPU, memory, and other resources. This can help you understand not just that a query is slow, but why it’s slow. Wait statistics are available in SQL Server 2017 and later.
How to Identify Regressed Queries in SQL Server (T-SQL)
Query regression occurs when a query that previously performed well suddenly becomes slower, often due to a plan change. SQL Server’s Query Store makes it easy to identify these regressions by comparing recent performance against historical baselines.
Finding the Most Resource-Intensive Queries in SQL Server
Identifying queries that consume the most resources can help you prioritize performance optimization efforts. In SQL Server you can use Query Store to track CPU time, duration, memory usage, and I/O for every query. This makes it easy to find the biggest resource consumers in your database.
How to Enable Query Store in SQL Server
Query Store is SQL Server’s built-in query performance tracking system that captures execution history, plans, and runtime statistics. From SQL Server 2022 it’s enabled by default for all newly created databases. But in earlier versions, it’s disabled by default, which means you’ll need to explicitly enable it on each database where you want to track query performance.
What is the Query Store in SQL Server?
Query Store is SQL Server’s built-in query performance tracking system. It captures a history of queries, their execution plans, and runtime statistics, storing everything in the database itself. It constantly records what’s happening so you can analyze performance issues after the fact.
Query performance issues can be notoriously hard to debug. A query runs fine for weeks, then suddenly it’s slow, and by the time you check, the problem has vanished or the execution plan is no longer in cache. SQL Server 2016 introduced Query Store to address this. Once enabled on a database, it continuously records query execution history, giving you the data you need to investigate performance problems after they happen. It won’t tell you what’s wrong or how to fix it, but at least you’ll have evidence to work with instead of flying blind.