Debugging SQL Query Performance with Query Store

Debugging Query Performance with Query Store

Write a SQL query to debug query performance using the Query Store feature.

Solution:

-- Enable Query Store for the database.
ALTER DATABASE MyDatabase SET QUERY_STORE = ON;

-- Retrieve query performance statistics from the Query Store.
SELECT 
    qs.query_id,
    qt.query_sql_text,
    rs.avg_duration,
    rs.execution_count
FROM sys.query_store_query qs
JOIN sys.query_store_plan qp ON qs.query_id = qp.query_id
JOIN sys.query_store_runtime_stats rs ON qp.plan_id = rs.plan_id
JOIN sys.query_store_query_text qt ON qs.query_text_id = qt.query_text_id
ORDER BY rs.avg_duration DESC;

Explanation:

• Purpose of the Query :
• The goal is to use the Query Store to analyze query performance and identify bottlenecks.
• Key Components :
• sys.query_store_*: Dynamic management views for Query Store data.
• Columns like avg_duration and execution_count provide insights.
• Why Use Query Store? :
• Query Store captures historical query performance data for analysis.
• It helps identify regressions and optimize queries over time.
• Real-World Application :
• Database administrators use Query Store to troubleshoot slow-running queries.

Additional Notes:

• Query Store is available in SQL Server 2016+ and Azure SQL Database.
• Regularly review and archive Query Store data to manage storage.
• Important Considerations:
• Enable Query Store only for databases requiring performance monitoring.

For more Practice: Solve these Related Problems:

• Write a SQL query to identify the top 5 most resource-intensive queries using the Query Store.
• Create a test case where Query Store data is used to debug a sudden drop in query performance.
• Write a SQL query to analyze query plan regressions captured by the Query Store over a specific time period.
• Debug a query performance issue by comparing runtime statistics of different execution plans in the Query Store.

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