Explanation

When starting XWiki with PostgreSQL, you may encounter the following message in the PostgreSQL logs:

Relation "hibernate_sequence" already exists

Cause

This message is expected and usually harmless. Because of a Hibernate limitation, XWiki attempts to create the hibernate_sequence sequence during startup without first checking whether it already exists in a database-independent way. If the sequence already exists, PostgreSQL reports the warning in the logs.

Solution

No action is required. This message can safely be ignored as long as XWiki starts correctly and operates normally.