diff --git a/graph/mongo/triplestore.go b/graph/mongo/triplestore.go
index 364d195..79fe38d 100644
--- a/graph/mongo/triplestore.go
+++ b/graph/mongo/triplestore.go
@@ -18,7 +18,6 @@ import (
 	"crypto/sha1"
 	"encoding/hex"
 	"hash"
-	"io"
 
 	"gopkg.in/mgo.v2"
 	"gopkg.in/mgo.v2/bson"
@@ -33,9 +32,6 @@ func init() {
 	graph.RegisterTripleStore("mongo", true, newTripleStore, createNewMongoGraph)
 }
 
-// Guarantee we satisfy graph.Bulkloader.
-var _ graph.BulkLoader = (*TripleStore)(nil)
-
 const DefaultDBName = "cayley"
 
 type TripleStore struct {
@@ -63,13 +59,21 @@ func createNewMongoGraph(addr string, options graph.Options) error {
 		Background: true,
 		Sparse:     true,
 	}
-	db.C("triples").EnsureIndex(indexOpts)
+	db.C("quads").EnsureIndex(indexOpts)
 	indexOpts.Key = []string{"Pred"}
-	db.C("triples").EnsureIndex(indexOpts)
+	db.C("quads").EnsureIndex(indexOpts)
 	indexOpts.Key = []string{"Obj"}
-	db.C("triples").EnsureIndex(indexOpts)
+	db.C("quads").EnsureIndex(indexOpts)
 	indexOpts.Key = []string{"Label"}
-	db.C("triples").EnsureIndex(indexOpts)
+	db.C("quads").EnsureIndex(indexOpts)
+	logOpts := mgo.Index{
+		Key:        []string{"LogID"},
+		Unique:     true,
+		DropDups:   false,
+		Background: true,
+		Sparse:     true,
+	}
+	db.C("log").EnsureIndex(logOpts)
 	return nil
 }
 
@@ -113,114 +117,121 @@ type MongoNode struct {
 	Size int    "Size"
 }
 
-func (qs *TripleStore) updateNodeBy(node_name string, inc int) {
-	var size MongoNode
-	node := qs.ValueOf(node_name)
-	err := qs.db.C("nodes").FindId(node).One(&size)
-	if err != nil {
-		if err.Error() == "not found" {
-			// Not found. Okay.
-			size.Id = node.(string)
-			size.Name = node_name
-			size.Size = inc
-		} else {
-			glog.Errorf("Error: %v", err)
-			return
-		}
-	} else {
-		size.Id = node.(string)
-		size.Name = node_name
-		size.Size += inc
-	}
-
-	// Removing something...
-	if inc < 0 {
-		if size.Size <= 0 {
-			err := qs.db.C("nodes").RemoveId(node)
-			if err != nil {
-				glog.Errorf("Error: %v while removing node %s", err, node_name)
-				return
-			}
-		}
-	}
-
-	_, err2 := qs.db.C("nodes").UpsertId(node, size)
-	if err2 != nil {
-		glog.Errorf("Error: %v", err)
-	}
+type MongoLogEntry struct {
+	LogID     int64  "LogID"
+	Action    string "Action"
+	Key       string "Key"
+	Timestamp int64
 }
 
-func (qs *TripleStore) writeTriple(t quad.Quad) bool {
+func (qs *TripleStore) updateNodeBy(node_name string, inc int) error {
+	node := qs.ValueOf(node_name)
+	doc := bson.M{
+		"_id":  node.(string),
+		"Name": node_name,
+	}
+	upsert := bson.M{
+		"$setOnInsert": doc,
+		"$inc": bson.M{
+			"Size": inc,
+		},
+	}
+
+	_, err := qs.db.C("nodes").UpsertId(node, upsert)
+	if err != nil {
+		glog.Errorf("Error updating node: %v", err)
+	}
+	return err
+}
+
+func (qs *TripleStore) updateTriple(t quad.Quad, id int64, proc graph.Procedure) error {
+	var setname string
+	if proc == graph.Add {
+		setname = "Added"
+	} else if proc == graph.Delete {
+		setname = "Deleted"
+	}
 	tripledoc := bson.M{
-		"_id":       qs.getIdForTriple(t),
 		"Subject":   t.Subject,
 		"Predicate": t.Predicate,
 		"Object":    t.Object,
 		"Label":     t.Label,
 	}
-	err := qs.db.C("triples").Insert(tripledoc)
+	upsert := bson.M{
+		"$setOnInsert": tripledoc,
+		"$push": bson.M{
+			setname: id,
+		},
+	}
+	_, err := qs.db.C("quads").UpsertId(qs.getIdForTriple(t), upsert)
 	if err != nil {
-		// Among the reasons I hate MongoDB. "Errors don't happen! Right guys?"
-		if err.(*mgo.LastError).Code == 11000 {
-			return false
-		}
 		glog.Errorf("Error: %v", err)
-		return false
 	}
-	return true
+	return err
 }
 
-func (qs *TripleStore) AddTriple(t quad.Quad) {
-	_ = qs.writeTriple(t)
-	qs.updateNodeBy(t.Subject, 1)
-	qs.updateNodeBy(t.Predicate, 1)
-	qs.updateNodeBy(t.Object, 1)
-	if t.Label != "" {
-		qs.updateNodeBy(t.Label, 1)
+func (qs *TripleStore) updateLog(d *graph.Delta) error {
+	var action string
+	if d.Action == graph.Add {
+		action = "Add"
+	} else {
+		action = "Delete"
 	}
+	entry := MongoLogEntry{
+		LogID:     d.ID,
+		Action:    action,
+		Key:       qs.getIdForTriple(d.Quad),
+		Timestamp: d.Timestamp.UnixNano(),
+	}
+	err := qs.db.C("log").Insert(entry)
+	if err != nil {
+		glog.Errorf("Error updating log: %v", err)
+	}
+	return err
 }
 
-func (qs *TripleStore) AddTripleSet(in []quad.Quad) {
+func (qs *TripleStore) ApplyDeltas(in []*graph.Delta) error {
 	qs.session.SetSafe(nil)
 	ids := make(map[string]int)
-	for _, t := range in {
-		wrote := qs.writeTriple(t)
-		if wrote {
-			ids[t.Subject]++
-			ids[t.Object]++
-			ids[t.Predicate]++
-			if t.Label != "" {
-				ids[t.Label]++
-			}
+	for _, d := range in {
+		err := qs.updateLog(d)
+		if err != nil {
+			return err
+		}
+	}
+	for _, d := range in {
+		err := qs.updateTriple(d.Quad, d.ID, d.Action)
+		if err != nil {
+			return err
+		}
+		var countdelta int
+		if d.Action == graph.Add {
+			countdelta = 1
+		} else {
+			countdelta = -1
+		}
+		ids[d.Quad.Subject] += countdelta
+		ids[d.Quad.Object] += countdelta
+		ids[d.Quad.Predicate] += countdelta
+		if d.Quad.Label != "" {
+			ids[d.Quad.Label] += countdelta
 		}
 	}
 	for k, v := range ids {
-		qs.updateNodeBy(k, v)
+		err := qs.updateNodeBy(k, v)
+		if err != nil {
+			return err
+		}
 	}
 	qs.session.SetSafe(&mgo.Safe{})
-}
-
-func (qs *TripleStore) RemoveTriple(t quad.Quad) {
-	err := qs.db.C("triples").RemoveId(qs.getIdForTriple(t))
-	if err == mgo.ErrNotFound {
-		return
-	} else if err != nil {
-		glog.Errorf("Error: %v while removing triple %v", err, t)
-		return
-	}
-	qs.updateNodeBy(t.Subject, -1)
-	qs.updateNodeBy(t.Predicate, -1)
-	qs.updateNodeBy(t.Object, -1)
-	if t.Label != "" {
-		qs.updateNodeBy(t.Label, -1)
-	}
+	return nil
 }
 
 func (qs *TripleStore) Quad(val graph.Value) quad.Quad {
 	var bsonDoc bson.M
-	err := qs.db.C("triples").FindId(val.(string)).One(&bsonDoc)
+	err := qs.db.C("quads").FindId(val.(string)).One(&bsonDoc)
 	if err != nil {
-		glog.Errorf("Error: Couldn't retrieve triple %s %v", val, err)
+		glog.Errorf("Error: Couldn't retrieve quad %s %v", val, err)
 	}
 	return quad.Quad{
 		bsonDoc["Subject"].(string),
@@ -231,7 +242,7 @@ func (qs *TripleStore) Quad(val graph.Value) quad.Quad {
 }
 
 func (qs *TripleStore) TripleIterator(d quad.Direction, val graph.Value) graph.Iterator {
-	return NewIterator(qs, "triples", d, val)
+	return NewIterator(qs, "quads", d, val)
 }
 
 func (qs *TripleStore) NodesAllIterator() graph.Iterator {
@@ -239,7 +250,7 @@ func (qs *TripleStore) NodesAllIterator() graph.Iterator {
 }
 
 func (qs *TripleStore) TriplesAllIterator() graph.Iterator {
-	return NewAllIterator(qs, "triples")
+	return NewAllIterator(qs, "quads")
 }
 
 func (qs *TripleStore) ValueOf(s string) graph.Value {
@@ -261,7 +272,8 @@ func (qs *TripleStore) NameOf(v graph.Value) string {
 }
 
 func (qs *TripleStore) Size() int64 {
-	count, err := qs.db.C("triples").Count()
+	// TODO(barakmich): Make size real; store it in the log, and retrieve it.
+	count, err := qs.db.C("quads").Count()
 	if err != nil {
 		glog.Errorf("Error: %v", err)
 		return 0
@@ -269,6 +281,15 @@ func (qs *TripleStore) Size() int64 {
 	return int64(count)
 }
 
+func (qs *TripleStore) Horizon() int64 {
+	var log MongoLogEntry
+	err := qs.db.C("log").Find(nil).Sort("-LogID").One(&log)
+	if err != nil {
+		glog.Errorf("Could not get Horizon from Mongo: %v", err)
+	}
+	return log.LogID
+}
+
 func compareStrings(a, b graph.Value) bool {
 	return a.(string) == b.(string)
 }
@@ -298,61 +319,4 @@ func (qs *TripleStore) TripleDirection(in graph.Value, d quad.Direction) graph.V
 	return val
 }
 
-func (qs *TripleStore) BulkLoad(dec quad.Unmarshaler) error {
-	if qs.Size() != 0 {
-		return graph.ErrCannotBulkLoad
-	}
-
-	qs.session.SetSafe(nil)
-	for {
-		q, err := dec.Unmarshal()
-		if err != nil {
-			if err != io.EOF {
-				return err
-			}
-			break
-		}
-		qs.writeTriple(q)
-	}
-
-	outputTo := bson.M{"replace": "nodes", "sharded": true}
-	glog.Infoln("Mapreducing")
-	job := mgo.MapReduce{
-		Map: `function() {
-      var len = this["_id"].length
-      var s_key = this["_id"].slice(0, len / 4)
-      var p_key = this["_id"].slice(len / 4, 2 * len / 4)
-      var o_key = this["_id"].slice(2 * len / 4, 3 * len / 4)
-      var c_key = this["_id"].slice(3 * len / 4)
-      emit(s_key, {"_id": s_key, "Name" : this.Subject, "Size" : 1})
-      emit(p_key, {"_id": p_key, "Name" : this.Predicate, "Size" : 1})
-      emit(o_key, {"_id": o_key, "Name" : this.Object, "Size" : 1})
-			if (this.Label != "") {
-				emit(c_key, {"_id": c_key, "Name" : this.Label, "Size" : 1})
-			}
-    }
-    `,
-		Reduce: `
-      function(key, value_list) {
-        out = {"_id": key, "Name": value_list[0].Name}
-        count = 0
-        for (var i = 0; i < value_list.length; i++) {
-          count = count + value_list[i].Size
-
-        }
-        out["Size"] = count
-        return out
-      }
-    `,
-		Out: outputTo,
-	}
-	qs.db.C("triples").Find(nil).MapReduce(&job, nil)
-	glog.Infoln("Fixing")
-	qs.db.Run(bson.D{{"eval", `function() { db.nodes.find().forEach(function (result) {
-    db.nodes.update({"_id": result._id}, result.value)
-  }) }`}, {"args", bson.D{}}}, nil)
-
-	qs.session.SetSafe(&mgo.Safe{})
-
-	return nil
-}
+// TODO(barakmich): Rewrite bulk loader. For now, iterating around blocks is the way we'll go about it.
diff --git a/writer/single.go b/writer/single.go
index 51641ca..0dc4882 100644
--- a/writer/single.go
+++ b/writer/single.go
@@ -22,6 +22,10 @@ import (
 	"github.com/google/cayley/quad"
 )
 
+func init() {
+	graph.RegisterWriter("single", NewSingleReplication)
+}
+
 type Single struct {
 	nextID int64
 	ts     graph.TripleStore
@@ -79,7 +83,3 @@ func (s *Single) RemoveQuad(q quad.Quad) error {
 	}
 	return s.ts.ApplyDeltas(deltas)
 }
-
-func init() {
-	graph.RegisterWriter("single", NewSingleReplication)
-}