Troubleshooting Azure SQL Database
This section provides guidance and solutions for common issues encountered when working with Azure SQL Database.
Common Issues and Solutions
1. Connectivity Problems
Symptoms:
- Cannot connect to the Azure SQL Database server.
- Connection timeouts.
- Firewall blocking access.
Solutions:
- Check Firewall Rules: Ensure your client IP address is allowed in the Azure SQL server's firewall settings. Navigate to the Azure portal, select your SQL server, go to "Networking" or "Firewalls and virtual networks".
- Verify Connection Strings: Double-check your connection string for typos, correct server name, database name, username, and password.
- Network Connectivity: Test general network connectivity to the Azure SQL Database endpoint using tools like
pingortelnet(though ping may be blocked, telnet to port 1433 is more indicative). - Service Status: Check the Azure Service Health dashboard for any ongoing incidents affecting Azure SQL Database in your region.
See also: Troubleshooting connectivity issues in Azure SQL Database.
2. Performance Degradation
Symptoms:
- Slow query execution times.
- High CPU utilization.
- Throttling errors (e.g.,
REQUEST_MINSEC_RESOURCE_GOVERNOR).
Solutions:
- Query Optimization: Analyze query execution plans, identify missing indexes, and rewrite inefficient queries. Use Azure SQL Analytics and Query Performance Insight.
- Resource Scaling: Consider scaling up your database tier (DTU or vCore) or storage if you are consistently hitting resource limits.
- Indexing: Ensure appropriate indexes are in place and maintain them regularly. Use the Database Advisor for index recommendations.
- Parameter Sniffing: Address parameter sniffing issues by using query hints or recompiling procedures.
- Check for Blocking: Identify and resolve blocking sessions that may be holding up other processes.
See also: Optimizing Performance.
3. Error Messages and Codes
Azure SQL Database can return various error messages and codes. Here are some common ones:
Error 100: Network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections.
Error 4060: Cannot open database "YourDatabase" requested by the login. The login failed.
Error 40501: The database is too small. Increase the database size to avoid this error.
For a comprehensive list of error messages and their explanations, refer to the official Azure SQL Database documentation on error messages.
4. Throttling and Resource Limits
Azure SQL Database uses resource governors to ensure fair resource sharing. When you exceed your allocated limits, requests can be throttled.
Common Throttling Metrics:
- CPU percentage
- Data IO percentage
- Log IO percentage
- DTU percentage (for DTU-based models)
- Workers (for vCore-based models)
Troubleshooting Steps:
- Monitor resource utilization using Azure Monitor and performance insights.
- Identify the queries or processes consuming the most resources.
- Optimize queries, add indexes, or scale up your database tier.
- Consider elastic pools for managing costs and performance across multiple databases.
Diagnostic Tools and Resources
- Azure Monitor: Provides metrics, logs, and alerts for your Azure SQL Database.
- Query Performance Insight: Helps identify top resource-consuming queries.
- SQL Server Management Studio (SSMS) / Azure Data Studio: Use these tools for detailed diagnostics, profiling, and query analysis.
- Azure Advisor: Offers recommendations for performance, security, and cost optimization.
Getting Help
If you are unable to resolve an issue using this documentation, consider the following resources:
- Microsoft Q&A: Post your questions and get help from the community and Microsoft experts.
- Azure Support: Open a support ticket for critical issues.