You might want to recover all archived projects, specially if you are planning to run a Jira Cloud Migration and want to make sure the archived projects are migrated. 

So if you want to know which projects are archived you can run this SQL query:

SELECT p.pkey 
FROM propertyentry pe
JOIN project p ON pe.entity_id = p.id
WHERE pe.property_key = 'jira.archiving.projects'
AND p.pkey IN ('ABC','PREM'); -- Replace with your project keys