Details on how aurora load balances read operations

Question

Hello,

I'm interested in learning more about how aurora **balances load inside the cluster**. I have an Aurora Mysql cluster with only one replica and my app is configured to point all read operations to the read only endpoint.

What I see in the monitoring tab is that the writer instance is under very low load while the replica is under heavy load. Maybe this is influenced by the type of application (lot's of read operations), but what I imagined was that, when on low load, the writer instance would also serve some read operations.

Can someone point me to the correct documentation?

Thanks a lot.

Accepted Answer

Hi.

If you check [Amazon Aurora connection management](https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Overview.Endpoints.html) it gives the answer you are looking for. Read operations using the reader endpoint only loadbalance between replica instances:

```
Use the reader endpoint for read operations, such as queries. 
By processing those statements on the read-only Aurora Replicas, 
this endpoint reduces the overhead on the primary instance. 
It also helps the cluster to scale the capacity to handle simultaneous 
SELECT queries, proportional to the number of Aurora Replicas in 
the cluster.
```

```
The reader endpoint load-balances connections to available 
Aurora Replicas in an Aurora DB cluster. 
It doesn't load-balance individual queries.
```

Details on how aurora load balances read operations

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