diff --git a/internal/querynodev2/metrics_info.go b/internal/querynodev2/metrics_info.go
index e2f1b9b5b0..0870198980 100644
--- a/internal/querynodev2/metrics_info.go
+++ b/internal/querynodev2/metrics_info.go
@@ -104,12 +104,15 @@ func getQuotaMetrics(node *QueryNode) (*metricsinfo.QueryNodeQuotaMetrics, error
 
 	minTsafeChannel, minTsafe := node.tSafeManager.Min()
 
+	collections := node.manager.Collection.List()
+
 	var totalGrowingSize int64
 	growingSegments := node.manager.Segment.GetBy(segments.WithType(segments.SegmentTypeGrowing))
 	growingGroupByCollection := lo.GroupBy(growingSegments, func(seg segments.Segment) int64 {
 		return seg.Collection()
 	})
-	for collection, segs := range growingGroupByCollection {
+	for _, collection := range collections {
+		segs := growingGroupByCollection[collection]
 		size := lo.SumBy(segs, func(seg segments.Segment) int64 {
 			return seg.MemSize()
 		})
@@ -122,7 +125,8 @@ func getQuotaMetrics(node *QueryNode) (*metricsinfo.QueryNodeQuotaMetrics, error
 	sealedGroupByCollection := lo.GroupBy(sealedSegments, func(seg segments.Segment) int64 {
 		return seg.Collection()
 	})
-	for collection, segs := range sealedGroupByCollection {
+	for _, collection := range collections {
+		segs := sealedGroupByCollection[collection]
 		size := lo.SumBy(segs, func(seg segments.Segment) int64 {
 			return seg.MemSize()
 		})
@@ -130,12 +134,6 @@ func getQuotaMetrics(node *QueryNode) (*metricsinfo.QueryNodeQuotaMetrics, error
 			fmt.Sprint(collection), segments.SegmentTypeSealed.String()).Set(float64(size))
 	}
 
-	allSegments := node.manager.Segment.GetBy()
-	collections := typeutil.NewUniqueSet()
-	for _, segment := range allSegments {
-		collections.Insert(segment.Collection())
-	}
-
 	return &metricsinfo.QueryNodeQuotaMetrics{
 		Hms: metricsinfo.HardwareMetrics{},
 		Rms: rms,
@@ -149,7 +147,7 @@ func getQuotaMetrics(node *QueryNode) (*metricsinfo.QueryNodeQuotaMetrics, error
 		GrowingSegmentsSize: totalGrowingSize,
 		Effect: metricsinfo.NodeEffect{
 			NodeID:        node.GetNodeID(),
-			CollectionIDs: collections.Collect(),
+			CollectionIDs: collections,
 		},
 	}, nil
 }
diff --git a/internal/querynodev2/segments/collection.go b/internal/querynodev2/segments/collection.go
index 89f12b463b..a181734187 100644
--- a/internal/querynodev2/segments/collection.go
+++ b/internal/querynodev2/segments/collection.go
@@ -25,6 +25,7 @@ package segments
 import "C"
 
 import (
+	"fmt"
 	"sync"
 	"unsafe"
 
@@ -39,11 +40,14 @@ import (
 	"github.com/milvus-io/milvus/internal/proto/segcorepb"
 	"github.com/milvus-io/milvus/pkg/common"
 	"github.com/milvus-io/milvus/pkg/log"
+	"github.com/milvus-io/milvus/pkg/metrics"
 	"github.com/milvus-io/milvus/pkg/util/indexparamcheck"
+	"github.com/milvus-io/milvus/pkg/util/paramtable"
 	"github.com/milvus-io/milvus/pkg/util/typeutil"
 )
 
 type CollectionManager interface {
+	List() []int64
 	Get(collectionID int64) *Collection
 	PutOrRef(collectionID int64, schema *schemapb.CollectionSchema, meta *segcorepb.CollectionIndexMeta, loadMeta *querypb.LoadMetaInfo)
 	Ref(collectionID int64, count uint32) bool
@@ -64,6 +68,13 @@ func NewCollectionManager() *collectionManager {
 	}
 }
 
+func (m *collectionManager) List() []int64 {
+	m.mut.RLock()
+	defer m.mut.RUnlock()
+
+	return lo.Keys(m.collections)
+}
+
 func (m *collectionManager) Get(collectionID int64) *Collection {
 	m.mut.RLock()
 	defer m.mut.RUnlock()
@@ -109,6 +120,16 @@ func (m *collectionManager) Unref(collectionID int64, count uint32) bool {
 			log.Info("release collection due to ref count to 0", zap.Int64("collectionID", collectionID))
 			delete(m.collections, collectionID)
 			DeleteCollection(collection)
+			metrics.QueryNodeEntitiesSize.DeleteLabelValues(
+				fmt.Sprint(paramtable.GetNodeID()),
+				fmt.Sprint(collectionID),
+				SegmentTypeSealed.String(),
+			)
+			metrics.QueryNodeEntitiesSize.DeleteLabelValues(
+				fmt.Sprint(paramtable.GetNodeID()),
+				fmt.Sprint(collectionID),
+				SegmentTypeGrowing.String(),
+			)
 			return true
 		}
 		return false
diff --git a/internal/querynodev2/segments/mock_collection_manager.go b/internal/querynodev2/segments/mock_collection_manager.go
index 5e11244a49..049b326c71 100644
--- a/internal/querynodev2/segments/mock_collection_manager.go
+++ b/internal/querynodev2/segments/mock_collection_manager.go
@@ -67,6 +67,49 @@ func (_c *MockCollectionManager_Get_Call) RunAndReturn(run func(int64) *Collecti
 	return _c
 }
 
+// List provides a mock function with given fields:
+func (_m *MockCollectionManager) List() []int64 {
+	ret := _m.Called()
+
+	var r0 []int64
+	if rf, ok := ret.Get(0).(func() []int64); ok {
+		r0 = rf()
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).([]int64)
+		}
+	}
+
+	return r0
+}
+
+// MockCollectionManager_List_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'List'
+type MockCollectionManager_List_Call struct {
+	*mock.Call
+}
+
+// List is a helper method to define mock.On call
+func (_e *MockCollectionManager_Expecter) List() *MockCollectionManager_List_Call {
+	return &MockCollectionManager_List_Call{Call: _e.mock.On("List")}
+}
+
+func (_c *MockCollectionManager_List_Call) Run(run func()) *MockCollectionManager_List_Call {
+	_c.Call.Run(func(args mock.Arguments) {
+		run()
+	})
+	return _c
+}
+
+func (_c *MockCollectionManager_List_Call) Return(_a0 []int64) *MockCollectionManager_List_Call {
+	_c.Call.Return(_a0)
+	return _c
+}
+
+func (_c *MockCollectionManager_List_Call) RunAndReturn(run func() []int64) *MockCollectionManager_List_Call {
+	_c.Call.Return(run)
+	return _c
+}
+
 // PutOrRef provides a mock function with given fields: collectionID, schema, meta, loadMeta
 func (_m *MockCollectionManager) PutOrRef(collectionID int64, schema *schemapb.CollectionSchema, meta *segcorepb.CollectionIndexMeta, loadMeta *querypb.LoadMetaInfo) {
 	_m.Called(collectionID, schema, meta, loadMeta)