KB11931: UserID's present in the IS_SESSION_STATS statistics table may not represent users that exist in the metadata

The USERID column in the IS_SESSION_STATS table depicts the GUID of the user who created the session. Certain userID's exist in the IS_SESSION_STATS statistics table, but users represented by these userID's do not exist in the metadata. This can be verified by querying the DSSMDOBJINFO table in the metadata for any of those userID's as follows:
 
The above query does not bring return any rows for those userID's. If the user represented by this userID exists in the metadata, one row will be returned for this query with OBJECT_TYPE = 34 and OBJECT_NAME as the name of the user.
 
It is true that the projects that are configured to log statistics are present in the above metadata.
 
There are two times when this situation can occur:
 

1. The users represented by the userID's existed in the metadata at the time when they created a session, but these users were subsequently deleted. In this situation, the user information will not be present in the DSSMDOBJINFO table, but the session information corresponding to those userID's will still exist in IS_SESSION_STATS table.
    
   
   
2. The other possibility is due to the use of guest accounts or anonymous authentication. When using anonymous authentication, users log in as "Guest" and do not need to provide a password. A GUID is generated for the guest user, and this session is recorded in the IS_SESSION_STATS table with the USERID column comprising this GUID. However, the guest user is not a named user in the metadata, and there is no information in the metadata corresponding to this GUID. A different GUID is generated each time that anonymous authentication is used. This can result in a multitude of userID's that exist in the IS_SESSION_STATS table that do not have corresponding entries in the DSSMDOBJINFO table.
    
   
   

Metadata Modification:
WARNING:
Manually editing values in the Strategy Metadata incorrectly may cause serious, project-wide problems that may make your project unusable. Since these are user-initiated changes, they are not covered by any Strategy warranty. Users are strongly encouraged to backup Metadata prior to any alteration.