Postgres allows multiple schemas on a database user's search path, that is users can query from tables in different schemas without the need of prefixing the tables in the query.
This can lead to confusion when after an unsuccessful upgrade DBA's restore the tables into a different schema (e.g. public) to Ambari's configured one. As a result, Ambari server may see corrupt data.
New consistency checks on server startup should warn the user in such situations.