arangosh> db.names.ensureIndex({ type: "persistent", fields: [ "first" ] }); { "deduplicate" : true, "fields" : [ "first" ], "id" : "names/111023", "isNewlyCreated" : true, "sparse" : false, "type" : "persistent", "unique" : false, "code" : 201 } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/111026", "_key" : "111026", "_rev" : "_YOn1f36--_" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/111030", "_key" : "111030", "_rev" : "_YOn1f36--B" } arangosh> db.names.save({ "first" : "John" }); { "_id" : "names/111033", "_key" : "111033", "_rev" : "_YOn1f36--D" } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/111036", "_key" : "111036", "_rev" : "_YOn1f4---_" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/111039", "_key" : "111039", "_rev" : "_YOn1f4---B" }