Here are ten ways to reduce Azure SQL Server costs when the database is used as the data source for a real-time web app written in .NET and hosted on Azure App Service:

1. Right-size your Azure SQL Database:

   • Choose the appropriate service tier and performance level based on your workload requirements.
   • Monitor and adjust the database size and performance level as needed to avoid overprovisioning.

2. Use elastic pools:

   • Consolidate multiple databases into an elastic pool to share resources and optimize costs.
   • Elastic pools allow you to manage the performance of multiple databases within a budget.

3. Implement efficient database design:

   • Normalize your database schema to reduce data redundancy and storage costs.
   • Optimize indexes and queries to improve query performance and reduce resource utilization.

4. Enable auto-pause and auto-resume:

   • Configure your Azure SQL Database to automatically pause when inactive and resume when needed.
   • This feature helps reduce costs during periods of low or no activity.

5. Utilize reserved capacity:

   • Purchase reserved capacity for Azure SQL Database to get significant discounts compared to pay-as-you-go pricing.
   • Reserved capacity allows you to commit to a specific amount of compute resources for a one or three-year term.

6. Implement caching mechanisms:

   • Use caching techniques, such as Azure Cache for Redis, to store frequently accessed data in memory.
   • Caching can reduce the load on the database and improve application performance.

7. Optimize database queries:

   • Analyze and optimize your database queries to minimize resource consumption.
   • Use query hints, parameterization, and efficient query patterns to improve query performance.

8. Implement data compression:

   • Enable data compression features in Azure SQL Database to reduce storage costs.
   • Compression can significantly reduce the size of your data while still allowing for efficient querying.

9. Monitor and optimize resource utilization:

   • Use Azure Monitor and SQL Database Advisor to monitor and analyze resource utilization.
   • Identify and address performance bottlenecks, inefficient queries, and other optimization opportunities.

10. Implement database sharding:

    • Consider sharding your database horizontally to distribute data across multiple databases.
    • Sharding can help scale your application and reduce the load on individual databases, potentially reducing costs.

Remember to regularly review and optimize your Azure SQL Database usage and costs. Continuously monitor performance metrics, query patterns, and resource utilization to identify areas for improvement and cost savings.

Additionally, take advantage of Azure cost management tools and alerts to set budgets, track spending, and receive notifications when cost thresholds are exceeded. This helps you stay within your budget and make informed decisions about resource allocation.