Scale for a PostgreSQL cluster

Currently, only vertical scaling for PostgreSQL is supported.

Vertical scaling

You can vertically scale a cluster by changing resource requirements and limits (CPU and storage). For example, if you need to change the resource demand from 1C2G to 2C4G, vertical scaling is what you need.

note

During the vertical scaling process, a concurrent restart is triggered and the leader pod may change after the restarting.

Before you start

Check whether the cluster status is Running. Otherwise, the following operations may fail.

kbcli cluster list <name>

Example

kbcli cluster list pg-cluster
>
NAME         NAMESPACE   CLUSTER-DEFINITION           VERSION             TERMINATION-POLICY   STATUS    CREATED-TIME
pg-cluster   default     postgresql-cluster           postgresql-14.7.0   Delete               Running   Mar 03,2023 18:00 UTC+0800

Steps

1. Change configuration. There are 3 ways to apply vertical scaling.

   Option 1. (Recommended) Use kbcli

   Configure the parameters --components, --memory, and --cpu and run the command.

   Example

   kbcli cluster vscale pg-cluster \
   --components="postgresql" \
   --memory="4Gi" --cpu="2" \
   • --components describes the component name ready for vertical scaling.
   • --memory describes the requested and limited size of the component memory.
   • --cpu describes the requested and limited size of the component CPU.

   Option 2. Create an OpsRequest

   Run the command below to apply an OpsRequest to the specified cluster. Configure the parameters according to your needs.

   kubectl apply -f - <<EOF
   apiVersion: apps.kubeblocks.io/v1alpha1
   kind: OpsRequest
   metadata:
     name: ops-vertical-scaling
   spec:
     clusterRef: pg-cluster
     type: VerticalScaling 
     verticalScaling:
     - componentName: postgresql
       requests:
         memory: "2Gi"
         cpu: "1000m"
       limits:
         memory: "4Gi"
         cpu: "2000m"
   EOF

   Option 3. Change the YAML file of the cluster

   Change the configuration of spec.components.resources in the YAML file. spec.components.resources controls the requirement and limit of resources and changing them triggers a vertical scaling.

   Example

   apiVersion: apps.kubeblocks.io/v1alpha1
   kind: Cluster
   metadata:
     name: pg-cluster
     namespace: default
   spec:
     clusterDefinitionRef: postgresql-cluster
     clusterVersionRef: postgre-14.7.0
     componentSpecs:
     - name: postgresql
       componentDefRef: postgresql
       replicas: 1
       resources: # Change the values of resources.
         requests:
           memory: "2Gi"
           cpu: "1000m"
         limits:
           memory: "4Gi"
           cpu: "2000m"
       volumeClaimTemplates:
       - name: data
         spec:
           accessModes:
             - ReadWriteOnce
           resources:
             requests:
               storage: 1Gi
     terminationPolicy: Halt

2. Validate the vertical scaling.

   Run the command below to check the cluster status to identify the vertical scaling status.

   kbcli cluster list <name>

   Example

   kbcli cluster list pg-cluster
   >
   NAME              NAMESPACE        CLUSTER-DEFINITION            VERSION                TERMINATION-POLICY   STATUS    CREATED-TIME
   pg-cluster        default          postgresql-cluster            postgresql-14.7.0      Delete               Running   Mar 03,2023 18:00 UTC+0800

   • STATUS=VerticalScaling: it means the vertical scaling is in progress.

   • STATUS=Running: it means the vertical scaling has been applied.

   • STATUS=Abnormal: it means the vertical scaling is abnormal. The reason may be the normal instances number is less than the total instance number or the leader instance is running properly while others are abnormal.

     To solve the problem, you can check manually to see whether resources are sufficient. If AutoScaling is supported, the system recovers when there are enough resources, otherwise, you can create enough resources and check the result with kubectl describe command.

     note

     Vertical scaling does not synchronize parameters related to CPU and memory and it is required to manually call the OpsRequest of configuration to change parameters accordingly. Refer to Configuration for instructions.

3. Check whether the corresponding resources change.

   kbcli cluster describe pg-cluster