arangosh> db.names.ensureIndex({ type: "persistent", fields: [ "first" ] }); { "deduplicate" : true, "fields" : [ "first" ], "id" : "names/15380", "isNewlyCreated" : true, "sparse" : false, "type" : "persistent", "unique" : false, "code" : 201 } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/15383", "_key" : "15383", "_rev" : "_VOyxoAC---" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/15387", "_key" : "15387", "_rev" : "_VOyxoAK---" } arangosh> db.names.save({ "first" : "John" }); { "_id" : "names/15390", "_key" : "15390", "_rev" : "_VOyxoAK--_" } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/15393", "_key" : "15393", "_rev" : "_VOyxoAO---" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/15396", "_key" : "15396", "_rev" : "_VOyxoAO--_" }