Azure SQL Database

Hi Fernando Gutierrez,
When you enable read-only mode on your Business Critical database, the system operates as a highly available cluster. This cluster comprises a primary replica responsible for handling all write operations and one or more secondary replicas that support synchronous data replication for read-only queries.

Identical Hardware Across Replicas: Both the primary (write endpoint) and the secondary (read-only endpoint) replicas are provisioned with equivalent hardware resources—including vCores, memory, and I/O performance. In essence, read-only connections access the same level of resources as write connections.

Distributed Architecture: The Business Critical tier is engineered to distribute workloads efficiently. When a connection is established with read-only intent (such as by specifying the Application Intent as ReadOnly), Azure’s routing mechanism automatically directs the query to one of the secondary replicas. This distribution not only optimizes performance but also enhances overall availability without compromising on resource capacity.

Automatic Routing and Load Distribution: This design ensures that the load is balanced across multiple replicas. Therefore, even though read-only operations are served by secondary replicas, they benefit from the same underlying resource specifications as the primary replica. The separation is purely intended to manage workload distribution rather than indicating any reduction in resource capabilities.

In Summary: Even in read-only mode, you benefit from the same high-performance resources as those used in write operations. The primary advantage of this approach is the efficient distribution of requests across multiple replicas, which helps improve overall performance and minimizes contention between read and write operations.

I hope this information helps. Please do let us know if you have any further queries. 

If this answers your query, do click "Accept the answer” for the same, which might be beneficial to other community members reading this thread. And, if you have any further query do let us know.