Obviously, no one should be accessing the clusters during the

upgrade. <application>pg_upgrade</> defaults to running servers

on port 50432 to avoid unintended client connections.

You can use the same port numbers for both clusters because the

old and new clusters will not be running at the same time.

You can use the same port number for both clusters when doing an

upgrade because the old and new clusters will not be running at the

same time. However, when checking an old running server, the old

and new port numbers must be different.

</para>

<para>