arangosh> db.names.ensureIndex({ type: "persistent", fields: [ "first" ] }); { "deduplicate" : true, "fields" : [ "first" ], "id" : "names/110159", "isNewlyCreated" : true, "sparse" : false, "type" : "persistent", "unique" : false, "code" : 201 } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/110162", "_key" : "110162", "_rev" : "_XUJzKpq--_" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/110166", "_key" : "110166", "_rev" : "_XUJzKpu--_" } arangosh> db.names.save({ "first" : "John" }); { "_id" : "names/110169", "_key" : "110169", "_rev" : "_XUJzKpu--B" } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/110172", "_key" : "110172", "_rev" : "_XUJzKpy--_" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/110175", "_key" : "110175", "_rev" : "_XUJzKpy--B" }