We imagine retrieving data extracted from corporate personnel records. We source EMPLOYEES with names, emails and managers. data 
Daily update from cron job on c2.com, user account ward. Upstream changes are only as needed and occasionally inconsistent.
Extracted data format. Hover for samples.
[] MAX 1000 {} NODE Employee name email manager => NODE Employee email
Merge with Source Code Control
create (s:EXPLAIN {props}) with s unwind {json} as obj merge (e:EMPLOYEE {email: obj.email}) on create set e.name=obj.name, e.manager=obj.manager merge (m:EMPLOYEE {email:coalesce(obj.manager,obj.email)}) merge (e)-[:MANAGER {source:s.name}]->(m)