Check configured users and active identities ​

Coordinator DB users are declared in the file selected by users_config. Inspect that configuration to determine which named credentials exist. The server does not create an implicit account when the file is missing, and usernames are case-sensitive.

An authenticated connection can inspect the identity recorded for active requests:

SELECT query_id, user, interface
FROM system.processes
ORDER BY user;

This is an observation of active requests, not a complete configured-user list. Query history records authenticated identities for earlier requests when logging admitted their events.

Each configured user has exactly one password form and can optionally have an HTTP API-key digest. Password and key changes require a server restart. Invalid explicit HTTP credentials do not fall back to the empty-password default user.

Roles, permission grants and settings profiles are unavailable. Listing several configured usernames therefore does not prove that those users have different SQL privileges. If an application requires separate access boundaries, enforce them through the application and the deployment that controls which database service can be reached.

See authentication, users_config and active identities.