title: Neo4j add property from CSV to a node
body: <p>I have a label Person which contains millions of nodes. The nodes have some properties and I am trying to add a new property to the nodes from a CSV file.
  I am trying to match them by the person's forename and surname but the query is too slow. The query is:</p>
  
  <p><code>USING PERIODIC COMMIT
  LOAD CSV WITH HEADERS FROM
  'file:///personaldata.csv' AS line1
  MATCH (p:Person {forename:line1.forename, surname:line1.surname})
  SET p.newPersonNumber=line1.newPersonNumber</code></p>
  
  <p>I left the query running for maybe an hour before I terminated it.
  Am I doing something wrong?
  Note that I have indexes on <code>forename</code> and <code>surname</code> .</p>