add a toggle for this option

pkg/cluster/cluster.go

@@ -634,8 +634,7 @@ func (c *Cluster) Update(oldSpec, newSpec *acidv1.Postgresql) error {
 		}
 	}()
 
-	// delete persistent volume claim after scale down
-	if oldSpec.Spec.NumberOfInstances > newSpec.Spec.NumberOfInstances {
+	if c.OpConfig.ShouldDeleteUnusedPVC && oldSpec.Spec.NumberOfInstances > newSpec.Spec.NumberOfInstances {
 		c.logger.Debug("deleting pvc of shut down pods")
 
 		for i := oldSpec.Spec.NumberOfInstances - 1; i >= newSpec.Spec.NumberOfInstances; i-- {

pkg/cluster/sync.go

@@ -111,8 +111,9 @@ func (c *Cluster) Sync(newSpec *acidv1.Postgresql) error {
 
 	// remove unused PVCs in case deleting them during scale down failed; see Update()
 	// the last pvc stays until the cluster is explicitly deleted as opposed to being scaled down to 0 pods
-	if c.getNumberOfInstances(&c.Spec) > 0 {
+	if c.OpConfig.ShouldDeleteUnusedPVC && c.getNumberOfInstances(&c.Spec) > 0 {
 
+		// XXX that also deletes PVC of pods shut down before this change is deployed
 		for i := c.getNumberOfInstances(&c.Spec); ; i++ {
 			podIndex := strconv.Itoa(int(i))
 			pvcName := "pgdata-" + c.Name + "-" + podIndex