You can dynamically expand a read replica depending on the load on the read replica.
With automatic scale out, the operator automatically extends the read replica according to the policy you specify.
The available policies are controlled by the CPU load or number of connections of read replica instance to automatically extend beyond a specified threshold.
Automatic scale out eliminates the need to use unnecessary resources for maximum potential load. It also reduces manual operations as the load increases.
Note
The automatic scale out feature adds replicas one at a time. In addition, additional replicas take time to service, depending on the environment and the amount of data stored. As a result, replica growth may not be able to keep up with the increased load.
Even if the automatic scale out feature increases the number of replicas, incoming requests are not given priority to those replicas. As a result, existing FEP instances may continue to be temporarily overloaded after the number of replicas increases.
The automatic scale out feature increases the number of replica requests that can be handled only by reference requests to the database. Requests with updates continue to be processed on the primary FEP instance. Therefore, the autoscale out feature may not reduce the load on the primary FEP instance.
Currently, the automatic scale out feature does not delete replicas (reduce the number of replicas). If the load decreases after the number of replicas increases due to a temporary increase in load, the number of replicas remains increased. If necessary, manually change the number of replicas.
You can scale out or scale in the read replica at any time. This can be done by manipulating the CR of the FEPCluster.
