diff --git a/storage/interface.go b/storage/interface.go
index f5fd19df8..eb2b5975f 100644
--- a/storage/interface.go
+++ b/storage/interface.go
@@ -180,6 +180,14 @@ type Appender interface {
 	ExemplarAppender
 }
 
+// GetRef is an extra interface on Appenders used by downstream projects
+// (e.g. Cortex) to avoid maintaining a parallel set of references.
+type GetRef interface {
+	// Returns reference number that can be used to pass to Appender.Append().
+	// 0 means the appender does not have a reference to this series.
+	GetRef(lset labels.Labels) uint64
+}
+
 // ExemplarAppender provides an interface for adding samples to exemplar storage, which
 // within Prometheus is in-memory only.
 type ExemplarAppender interface {
diff --git a/tsdb/db.go b/tsdb/db.go
index 8d58f5c58..b8b3c9970 100644
--- a/tsdb/db.go
+++ b/tsdb/db.go
@@ -795,6 +795,15 @@ type dbAppender struct {
 	db *DB
 }
 
+var _ storage.GetRef = dbAppender{}
+
+func (a dbAppender) GetRef(lset labels.Labels) uint64 {
+	if g, ok := a.Appender.(storage.GetRef); ok {
+		return g.GetRef(lset)
+	}
+	return 0
+}
+
 func (a dbAppender) Commit() error {
 	err := a.Appender.Commit()
 
diff --git a/tsdb/head.go b/tsdb/head.go
index cad73e23a..4f4e8d51d 100644
--- a/tsdb/head.go
+++ b/tsdb/head.go
@@ -1107,6 +1107,15 @@ func (a *initAppender) AppendExemplar(ref uint64, l labels.Labels, e exemplar.Ex
 	return a.app.AppendExemplar(ref, l, e)
 }
 
+var _ storage.GetRef = &initAppender{}
+
+func (a *initAppender) GetRef(lset labels.Labels) uint64 {
+	if g, ok := a.app.(storage.GetRef); ok {
+		return g.GetRef(lset)
+	}
+	return 0
+}
+
 func (a *initAppender) Commit() error {
 	if a.app == nil {
 		return nil
@@ -1331,6 +1340,16 @@ func (a *headAppender) AppendExemplar(ref uint64, _ labels.Labels, e exemplar.Ex
 	return s.ref, nil
 }
 
+var _ storage.GetRef = &headAppender{}
+
+func (a *headAppender) GetRef(lset labels.Labels) uint64 {
+	s := a.head.series.getByHash(lset.Hash(), lset)
+	if s == nil {
+		return 0
+	}
+	return s.ref
+}
+
 func (a *headAppender) log() error {
 	if a.head.wal == nil {
 		return nil