While setting up the example scenarios the Secret seems unnecessary? Is it really used?

1. CREATE SECRET TO CONNECT TO DATABASE (ADJUST TO YOUR VALUES)
   oc create -f - <<EOF
   apiVersion: v1
   kind: Secret
   metadata:
   name: postgresql
   type: Opaque
   stringData:
   database-user: user
   database-name: sampledb
   database-password: mypassword
   EOF

Also the following steps can be shortened:
oc get pods
oc rsh postgres-xxxxx

to
oc rsh $(oc get pods -o name -l app=postgresql)