diff --git a/segment_vector.go b/segment_vector.go
index cf462f3..2b3044a 100644
--- a/segment_vector.go
+++ b/segment_vector.go
@@ -22,6 +22,7 @@ import (
 
 	"github.com/RoaringBitmap/roaring/v2"
 	index "github.com/blevesearch/bleve_index_api"
+	"github.com/blevesearch/go-faiss"
 )
 
 type VecPostingsList interface {
@@ -76,6 +77,12 @@ type VectorIndex interface {
 	ObtainKCentroidCardinalitiesFromIVFIndex(limit int, descending bool) ([]index.CentroidCardinality, error)
 }
 
+// refactor this?
+type CentroidIndexSegment interface {
+	Segment
+	GetCoarseQuantizer(field string) (*faiss.IndexImpl, error)
+}
+
 type VectorSegment interface {
 	Segment
 	InterpretVectorIndex(field string, except *roaring.Bitmap) (VectorIndex, error)