updateLinksExample

db._drop("fromCollection");
db._drop("toCollection");
db._drop("edgeCollection");
var fromCollection = db._create("fromCollection", {numberOfShards:2})
var toCollection = db._create("toCollection", {numberOfShards:2})
fromCollection.ensureIndex({type:"hash",unique:false,fields:["fromAttributeValue"]});
toCollection.ensureIndex({type:"hash",unique:false,fields:["toAttributeValue"]});
fromCollection.ensureIndex({type:"skiplist",unique:false,fields:["timeStamp"]});
toCollection.ensureIndex({type:"skiplist",unique:false,fields:["timeStamp"]});
var edgeCollection = db._createEdgeCollection("edgeCollection", {numberOfShards:2});

function update(lastImport) {
  db._explain(`FOR fromItem IN fromCollection
                 FILTER fromItem.timeStamp > @lastRun
                 FOR toItem IN toCollection
                   FILTER fromItem.fromAttributeValue == toItem.toAttributeValue
                   INSERT { _from: fromItem._id, _to: toItem._id, otherAttributes: {}} INTO edgeCollection`,
              {lastRun:lastImport});
  db._query(`FOR fromItem IN fromCollection
               FILTER fromItem.timeStamp > @lastRun
               FOR toItem IN toCollection
                 FILTER fromItem.fromAttributeValue == toItem.toAttributeValue
                 INSERT { _from: fromItem._id, _to: toItem._id, otherAttributes: {}} INTO edgeCollection`,
            {lastRun:lastImport}).toArray();
  db._explain(`FOR toItem IN toCollection
                 FILTER toItem.timeStamp > @lastRun
                 FOR fromItem IN fromCollection
                   FILTER fromItem.fromAttributeValue == toItem.toAttributeValue
                   FILTER fromItem.timeStamp <= @lastRun
                   INSERT { _from: fromItem._id, _to: toItem._id, otherAttributes: {}} INTO edgeCollection`,
              {lastRun:lastImport});
  db._query(`FOR toItem IN toCollection
               FILTER toItem.timeStamp > @lastRun
               FOR fromItem IN fromCollection
                 FILTER fromItem.fromAttributeValue == toItem.toAttributeValue
                 FILTER fromItem.timeStamp <= @lastRun
                 INSERT { _from: fromItem._id, _to: toItem._id, otherAttributes: {}} INTO edgeCollection`,
            {lastRun:lastImport});
}

fromCollection.insert({fromAttributeValue: 1, timeStamp:1});
fromCollection.insert({fromAttributeValue: 1, timeStamp:1});
fromCollection.insert({fromAttributeValue: 2, timeStamp:1});
toCollection.insert({toAttributeValue: 1, timeStamp:1});
toCollection.insert({toAttributeValue: 2, timeStamp:1});
toCollection.insert({toAttributeValue: 3, timeStamp:1});

update(0);

fromCollection.insert({fromAttributeValue: 4, timeStamp:2});
fromCollection.insert({fromAttributeValue: 4, timeStamp:2});
fromCollection.insert({fromAttributeValue: 5, timeStamp:2});
toCollection.insert({toAttributeValue: 4, timeStamp:2});
toCollection.insert({toAttributeValue: 5, timeStamp:2});
toCollection.insert({toAttributeValue: 6, timeStamp:2});

update(1);