PostgreSQL: Having multiple instances of an application should I use one database per instance or one schema per instance?

We have a web application that will be installed multiple times on a server. How should I organize the database for this case? Should I use one database per instance or one schema per instance?

Option 1:

  • DB: appname_customername1, SCHEMA: appname
  • DB: appname_customername2, SCHEMA: appname
  • DB: appname_customername3, SCHEMA: appname

Option 2:

  • DB: application_name, SCHEMA: application_name_application_name1
  • DB: application_name, SCHEMA: application_name_appername2
  • DB: application_name, SCHEMA: application_name_client_name3