Complex operations in this context refer to more than simple upgrades, scaling up or down; they involve a mix of these actions. Kubernetes' declarative API mandates efficient implementation of such operations, and the operator is designed to support them.

To illustrate, we can simultaneously

1. Change the CN image to polardbx/polardbx-sql:v2.0
2. Adjust CDC configuration to 8C32G
3. Increase the number of nodes in DN to 3

Likewise, these changes can be made using kubectl edit or kubectl patch. In this demonstration, we showcase the use of kubectl patch.

First, prepare a patch file,

spec:
  topology:
    nodes:
      cn:
        template:
          image: polardbx/polardbx-sql:v2.0
      dn:
        replicas: 3
      cdc:
        template:
          resources:
            limits:
              cpu: 8
              memory: 32Gi

Execute the following command to apply these changes:

kubectl patch --type='merge' pxc polardbx-test --patch-file patch.yaml

Now, observe the simultaneous changes in CN, DN, CDC, and the ongoing data migration:

kubectl get pxc polardbx-test -o wide
NAME           PROTOCOL   GMS   CN    DN    CDC   PHASE     DISK       STAGE                       REBALANCE   VERSION                            AGE
polardbx-test  8.0        1/1   1/2   2/3   1/2   Upgrading 22.6 GiB                                8.0.3-PXC-5.4.13-20220418/8.0.18   35d

kubectl get pxc polardbx-test -o wide
NAME           PROTOCOL   GMS   CN    DN    CDC   PHASE     DISK       STAGE                       REBALANCE   VERSION                            AGE
polardbx-test  8.0        1/1   2/2   3/3   2/2   Upgrading 22.6 GiB   RebalanceWatch   50%         8.0.3-PXC-5.4.13-20220418/8.0.18   35d

Note: As explained in "Uninterruptible Scenarios," data migration cannot be interrupted.