diff --git a/internal/distributed/queryservice/service.go b/internal/distributed/queryservice/service.go
index b6ddde255d779cb0c51662e3950d2d95247b6b0e..06687170d7e6b90c3eeeba7e628644f9301ddf50 100644
--- a/internal/distributed/queryservice/service.go
+++ b/internal/distributed/queryservice/service.go
@@ -35,7 +35,7 @@ type Server struct {
 func (s *Server) Init() error {
 	log.Println("query service init")
 	if err := s.queryService.Init(); err != nil {
-		panic(err)
+		return err
 	}
 	s.queryService.SetEnableGrpc(true)
 	return nil
diff --git a/internal/proto/query_service.proto b/internal/proto/query_service.proto
index 7a8b837b45d7d659c01163532fecbaa7208e9d42..aeba557f58c27c0e0042aeef154eda3bf65f659a 100644
--- a/internal/proto/query_service.proto
+++ b/internal/proto/query_service.proto
@@ -124,7 +124,7 @@ message LoadSegmentRequest {
   int64 partitionID = 4;
   repeated int64 segmentIDs = 5;
   repeated int64 fieldIDs = 6;
-  data.SegmentStateInfo last_segment_state = 7;
+  repeated data.SegmentStateInfo segment_states = 7;
 }
 
 message ReleaseSegmentRequest {
diff --git a/internal/proto/querypb/query_service.pb.go b/internal/proto/querypb/query_service.pb.go
index 64d1bb5b438d590d2e036f699473520002b09ae8..833984a93a0bff1f2717c69738f86a79d45081e9 100644
--- a/internal/proto/querypb/query_service.pb.go
+++ b/internal/proto/querypb/query_service.pb.go
@@ -972,16 +972,16 @@ func (m *WatchDmChannelsRequest) GetChannelIDs() []string {
 }
 
 type LoadSegmentRequest struct {
-	Base                 *commonpb.MsgBase        `protobuf:"bytes,1,opt,name=base,proto3" json:"base,omitempty"`
-	DbID                 int64                    `protobuf:"varint,2,opt,name=dbID,proto3" json:"dbID,omitempty"`
-	CollectionID         int64                    `protobuf:"varint,3,opt,name=collectionID,proto3" json:"collectionID,omitempty"`
-	PartitionID          int64                    `protobuf:"varint,4,opt,name=partitionID,proto3" json:"partitionID,omitempty"`
-	SegmentIDs           []int64                  `protobuf:"varint,5,rep,packed,name=segmentIDs,proto3" json:"segmentIDs,omitempty"`
-	FieldIDs             []int64                  `protobuf:"varint,6,rep,packed,name=fieldIDs,proto3" json:"fieldIDs,omitempty"`
-	LastSegmentState     *datapb.SegmentStateInfo `protobuf:"bytes,7,opt,name=last_segment_state,json=lastSegmentState,proto3" json:"last_segment_state,omitempty"`
-	XXX_NoUnkeyedLiteral struct{}                 `json:"-"`
-	XXX_unrecognized     []byte                   `json:"-"`
-	XXX_sizecache        int32                    `json:"-"`
+	Base                 *commonpb.MsgBase          `protobuf:"bytes,1,opt,name=base,proto3" json:"base,omitempty"`
+	DbID                 int64                      `protobuf:"varint,2,opt,name=dbID,proto3" json:"dbID,omitempty"`
+	CollectionID         int64                      `protobuf:"varint,3,opt,name=collectionID,proto3" json:"collectionID,omitempty"`
+	PartitionID          int64                      `protobuf:"varint,4,opt,name=partitionID,proto3" json:"partitionID,omitempty"`
+	SegmentIDs           []int64                    `protobuf:"varint,5,rep,packed,name=segmentIDs,proto3" json:"segmentIDs,omitempty"`
+	FieldIDs             []int64                    `protobuf:"varint,6,rep,packed,name=fieldIDs,proto3" json:"fieldIDs,omitempty"`
+	SegmentStates        []*datapb.SegmentStateInfo `protobuf:"bytes,7,rep,name=segment_states,json=segmentStates,proto3" json:"segment_states,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}                   `json:"-"`
+	XXX_unrecognized     []byte                     `json:"-"`
+	XXX_sizecache        int32                      `json:"-"`
 }
 
 func (m *LoadSegmentRequest) Reset()         { *m = LoadSegmentRequest{} }
@@ -1051,9 +1051,9 @@ func (m *LoadSegmentRequest) GetFieldIDs() []int64 {
 	return nil
 }
 
-func (m *LoadSegmentRequest) GetLastSegmentState() *datapb.SegmentStateInfo {
+func (m *LoadSegmentRequest) GetSegmentStates() []*datapb.SegmentStateInfo {
 	if m != nil {
-		return m.LastSegmentState
+		return m.SegmentStates
 	}
 	return nil
 }
@@ -1395,91 +1395,90 @@ func init() {
 func init() { proto.RegisterFile("query_service.proto", fileDescriptor_5fcb6756dc1afb8d) }
 
 var fileDescriptor_5fcb6756dc1afb8d = []byte{
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+	0x39, 0x07, 0xeb, 0x4e, 0xaf, 0x47, 0x0c, 0x4e, 0x1d, 0xfb, 0xf9, 0x49, 0x41, 0x90, 0x37, 0x3b,
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+	0x8b, 0x46, 0xa8, 0xaa, 0xd9, 0xf0, 0x7c, 0xce, 0xad, 0xe4, 0xb4, 0xf8, 0x26, 0xfe, 0x4e, 0x81,
+	0xc5, 0x4f, 0x1d, 0xdd, 0x3c, 0x23, 0xa7, 0x10, 0x86, 0x52, 0x14, 0xb0, 0x96, 0x13, 0xff, 0x62,
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+	0xbc, 0x00, 0x6c, 0xe9, 0x2e, 0xa7, 0xe7, 0x63, 0x42, 0xdf, 0xcf, 0xb0, 0x88, 0x05, 0xd3, 0x64,
+	0x00, 0x86, 0x52, 0x7f, 0xa8, 0xe9, 0x38, 0x01, 0x62, 0x7b, 0xd8, 0x82, 0x4a, 0x88, 0xe6, 0x1d,
+	0x27, 0x0c, 0x5d, 0x85, 0xb9, 0x88, 0x88, 0x00, 0xcc, 0x69, 0xd1, 0x2d, 0xf4, 0x21, 0xcc, 0x78,
+	0x10, 0x44, 0xf8, 0x57, 0x5e, 0xc3, 0xf5, 0xd1, 0xfa, 0x53, 0x8f, 0x6b, 0xd5, 0xfc, 0x03, 0xf8,
+	0x37, 0x05, 0x96, 0x12, 0x78, 0x2f, 0x9d, 0xe5, 0x11, 0x5e, 0xf2, 0x12, 0x5e, 0xfe, 0x54, 0x60,
+	0x79, 0xc4, 0xd0, 0x69, 0x82, 0xb1, 0x03, 0x4b, 0x21, 0x40, 0xdb, 0x24, 0xcc, 0x70, 0x69, 0xdf,
+	0xfb, 0xf6, 0xc3, 0x32, 0xb7, 0xf6, 0x66, 0x3a, 0x89, 0x4c, 0x5b, 0x0c, 0x55, 0x34, 0x22, 0x1a,
+	0xf0, 0xaf, 0x0a, 0x2c, 0x78, 0x97, 0xf8, 0xfc, 0x32, 0x77, 0x22, 0x4e, 0x7f, 0x57, 0x60, 0x39,
+	0xb8, 0xe7, 0xff, 0x73, 0x4b, 0x7f, 0x56, 0x40, 0x5d, 0x77, 0x89, 0xce, 0xc9, 0xe7, 0x5e, 0x1c,
+	0xd6, 0xf7, 0x74, 0xdb, 0x26, 0xbd, 0xe9, 0x12, 0xe0, 0x3a, 0x54, 0x5c, 0xdf, 0xd9, 0xb6, 0xe1,
+	0xeb, 0x13, 0xa6, 0x17, 0xb5, 0x72, 0xb0, 0x1d, 0xa0, 0xa0, 0xb7, 0xa1, 0xec, 0x12, 0x36, 0xe8,
+	0x1d, 0xcb, 0xe5, 0x84, 0xdc, 0x45, 0x7f, 0x37, 0x10, 0xc3, 0xbf, 0x28, 0xb0, 0x7c, 0xc7, 0x34,
+	0xa3, 0x06, 0x4e, 0x71, 0x97, 0x6e, 0xc1, 0xa5, 0x84, 0x75, 0x01, 0xb5, 0x45, 0xad, 0x1a, 0xb7,
+	0xaf, 0xd9, 0x40, 0x37, 0xa0, 0x1a, 0xb7, 0x30, 0xa0, 0xba, 0xa8, 0x55, 0x62, 0x36, 0x36, 0x1b,
+	0xf8, 0x6f, 0x05, 0x54, 0x8d, 0x58, 0xce, 0x3e, 0x91, 0x1a, 0xfa, 0x5c, 0x4c, 0x0e, 0xbd, 0xcb,
+	0x4e, 0xe7, 0x5d, 0xee, 0x14, 0xde, 0xe5, 0xe5, 0xde, 0x3d, 0x86, 0xa5, 0x87, 0x3a, 0x37, 0xf6,
+	0x1a, 0xd6, 0xf4, 0x11, 0xb8, 0x02, 0x10, 0xe2, 0xf9, 0x45, 0xa1, 0xa8, 0x45, 0x76, 0xf0, 0x1f,
+	0x59, 0x40, 0xde, 0x25, 0x6f, 0x91, 0xae, 0x45, 0x6c, 0xfe, 0xf2, 0x2f, 0x4e, 0xe2, 0x5d, 0xc8,
+	0x8f, 0xbe, 0x0b, 0x57, 0x00, 0x98, 0x6f, 0x9d, 0xe7, 0xc2, 0x8c, 0xb8, 0x58, 0x91, 0x1d, 0xa4,
+	0xc2, 0x85, 0x5d, 0x4a, 0x7a, 0xa6, 0xf7, 0xb7, 0x20, 0xfe, 0x86, 0x6b, 0xf4, 0x09, 0x94, 0x03,
+	0xc9, 0xb6, 0x78, 0x2a, 0x58, 0x6d, 0x56, 0x56, 0x17, 0xbd, 0x4e, 0xb5, 0x1e, 0x50, 0x20, 0x8a,
+	0x62, 0xd3, 0xde, 0x75, 0xb4, 0x8b, 0x2c, 0xb2, 0xc3, 0xf0, 0xbf, 0x0a, 0x2c, 0x06, 0x85, 0xe6,
+	0xdc, 0xd8, 0x9a, 0xa0, 0xcc, 0x4c, 0xc3, 0x17, 0xfe, 0x51, 0x81, 0xe5, 0x75, 0xc7, 0xea, 0x3b,
+	0x76, 0xe8, 0xf7, 0x74, 0xf5, 0xe9, 0x23, 0xff, 0x10, 0x19, 0x36, 0xc7, 0xd7, 0xc6, 0x34, 0xc7,
+	0x49, 0xd0, 0xe0, 0x14, 0xfe, 0x47, 0x81, 0xb9, 0x80, 0x6d, 0x2f, 0x26, 0xe8, 0x32, 0x14, 0x43,
+	0x57, 0x82, 0x26, 0xe2, 0x78, 0x63, 0x84, 0xc2, 0x6c, 0x7a, 0xc2, 0xe5, 0x46, 0x13, 0xee, 0x15,
+	0xb8, 0x60, 0x11, 0xab, 0xcd, 0xe8, 0x11, 0x09, 0xf2, 0x71, 0xd6, 0x22, 0x56, 0x8b, 0x1e, 0x11,
+	0xef, 0x97, 0x3d, 0xb0, 0xda, 0xae, 0x73, 0xe0, 0x31, 0x2b, 0x7e, 0xd9, 0x03, 0x4b, 0x73, 0x0e,
+	0x18, 0x7a, 0x0d, 0x80, 0xda, 0x26, 0x79, 0xd6, 0xb6, 0x75, 0x8b, 0xd4, 0x0a, 0xe2, 0x6a, 0x17,
+	0xc5, 0xce, 0xa6, 0x6e, 0x11, 0x54, 0x83, 0x59, 0xb1, 0x68, 0x36, 0x6a, 0xb3, 0xfe, 0xc1, 0x60,
+	0x89, 0x77, 0x01, 0x45, 0x3c, 0x9c, 0xea, 0xaa, 0x47, 0xe2, 0x9e, 0x4d, 0xc6, 0xdd, 0x6b, 0xca,
+	0xe7, 0x63, 0x40, 0xd3, 0xc4, 0xf5, 0x7d, 0x98, 0xa1, 0xf6, 0xae, 0x33, 0xec, 0x33, 0x5e, 0x97,
+	0xf5, 0x19, 0x51, 0x30, 0x5f, 0xfa, 0xe6, 0x11, 0x94, 0xe3, 0xdd, 0x07, 0x2a, 0xc1, 0x85, 0x4d,
+	0x87, 0xdf, 0x7b, 0x46, 0x19, 0xaf, 0x66, 0x50, 0x19, 0x60, 0xd3, 0xe1, 0x5b, 0x2e, 0x61, 0xc4,
+	0xe6, 0x55, 0x05, 0x01, 0x14, 0x3e, 0xb3, 0x1b, 0x94, 0x3d, 0xa9, 0x66, 0xd1, 0x7c, 0xd0, 0x54,
+	0xea, 0xbd, 0xa6, 0x7d, 0x9f, 0x58, 0x8e, 0x7b, 0x58, 0xcd, 0x79, 0xc7, 0xc3, 0x55, 0x1e, 0x55,
+	0xa1, 0x14, 0x8a, 0x6c, 0x6c, 0x3d, 0xa8, 0xce, 0xa0, 0x22, 0xcc, 0xf8, 0x9f, 0x85, 0xb5, 0x1f,
+	0x00, 0x4a, 0xe2, 0xb9, 0x68, 0xf9, 0x23, 0x29, 0x32, 0xa0, 0x14, 0x1d, 0x05, 0xd1, 0x75, 0x99,
+	0x13, 0x92, 0x71, 0x55, 0x5d, 0x49, 0x17, 0xf4, 0xb9, 0xc5, 0x19, 0xf4, 0x18, 0x2a, 0xf1, 0xf9,
+	0x8b, 0xa1, 0x1b, 0x52, 0xb2, 0x64, 0x33, 0xa0, 0x7a, 0x73, 0x12, 0xd1, 0x10, 0xab, 0x0b, 0xe5,
+	0x58, 0xa3, 0xcf, 0xd0, 0xca, 0xb8, 0xf3, 0xc9, 0x56, 0x49, 0xbd, 0x31, 0x81, 0x64, 0x08, 0xf4,
+	0x05, 0x94, 0x63, 0x9d, 0xe1, 0x18, 0x20, 0x59, 0xf7, 0xa8, 0x9e, 0x94, 0x5e, 0x38, 0x83, 0xda,
+	0x70, 0x29, 0xd9, 0xcd, 0x31, 0x74, 0x4b, 0x4e, 0xb8, 0xb4, 0xe9, 0x4b, 0x03, 0xd8, 0xf1, 0x6d,
+	0x3f, 0x26, 0x50, 0x1e, 0x0f, 0xe9, 0xf8, 0x9a, 0xa6, 0xfb, 0xeb, 0xd0, 0xf8, 0x88, 0xfa, 0x77,
+	0x4e, 0x30, 0xfe, 0xd4, 0x08, 0x1d, 0x40, 0xa3, 0x2d, 0x24, 0x52, 0xa5, 0x87, 0xee, 0x59, 0x7d,
+	0x7e, 0xa8, 0xd6, 0x65, 0xf0, 0xe3, 0xdb, 0x50, 0x9c, 0x41, 0x0f, 0x01, 0x6d, 0x10, 0xbe, 0x4d,
+	0x2d, 0xb2, 0x4d, 0x8d, 0x27, 0x93, 0x60, 0x24, 0x9e, 0xd3, 0x60, 0xd1, 0xe2, 0x2e, 0xb5, 0xbb,
+	0xb1, 0xb4, 0x59, 0xd8, 0x20, 0xa2, 0xc2, 0x53, 0xc6, 0xa9, 0xc1, 0x5e, 0xa0, 0x6a, 0x47, 0xd8,
+	0x9c, 0x1c, 0x3a, 0x6f, 0x4e, 0x32, 0xfe, 0x04, 0xc4, 0xdf, 0x9a, 0x48, 0x36, 0x04, 0xdc, 0x11,
+	0x80, 0x89, 0x67, 0xeb, 0x44, 0x4f, 0x26, 0x7c, 0xfa, 0x70, 0x06, 0x19, 0x50, 0xf6, 0x78, 0x8a,
+	0x3c, 0x7b, 0xd7, 0xd2, 0xea, 0x6b, 0xe0, 0xc4, 0xf5, 0x54, 0xb9, 0xa1, 0x03, 0x6b, 0x7f, 0x15,
+	0xa0, 0x28, 0x12, 0x40, 0xd4, 0xbe, 0x33, 0x8b, 0xf9, 0x36, 0x54, 0x82, 0x98, 0xbf, 0xc8, 0x70,
+	0xb7, 0x4f, 0xcd, 0xbe, 0x34, 0xbc, 0x63, 0x5a, 0x1d, 0x9c, 0x41, 0x8f, 0xa0, 0x92, 0x18, 0x83,
+	0xe4, 0x45, 0x68, 0xcc, 0xac, 0x94, 0x76, 0x8d, 0x0d, 0x40, 0xa3, 0xf3, 0x0b, 0xaa, 0xcb, 0x2b,
+	0xc5, 0xb8, 0x39, 0x27, 0x0d, 0xe4, 0x2b, 0xa8, 0x24, 0xe6, 0x08, 0xf9, 0x85, 0x90, 0x0f, 0x1b,
+	0x69, 0xda, 0x1f, 0x40, 0x29, 0x32, 0x38, 0x30, 0x79, 0x8a, 0x8e, 0x8e, 0x16, 0x69, 0x6a, 0xbf,
+	0x84, 0x4a, 0xbc, 0xc9, 0x1e, 0xf3, 0x5e, 0x4a, 0x3b, 0xf1, 0x74, 0xda, 0xcf, 0xfe, 0x62, 0xdd,
+	0xbd, 0xb3, 0xf3, 0x71, 0x97, 0xf2, 0xbd, 0x41, 0xc7, 0x83, 0x5f, 0x3d, 0xa2, 0xbd, 0x1e, 0x3d,
+	0xe2, 0xc4, 0xd8, 0x5b, 0xf5, 0x35, 0xbc, 0x6b, 0x52, 0xc6, 0x5d, 0xda, 0x19, 0x70, 0x62, 0xae,
+	0x0e, 0x8b, 0xc0, 0xaa, 0x50, 0xbb, 0x2a, 0xd4, 0xf6, 0x3b, 0x9d, 0x82, 0x58, 0xde, 0xfe, 0x2f,
+	0x00, 0x00, 0xff, 0xff, 0x36, 0xce, 0x45, 0x9b, 0x98, 0x17, 0x00, 0x00,
 }
 
 // Reference imports to suppress errors if they are not otherwise used.
diff --git a/internal/querynode/query_node.go b/internal/querynode/query_node.go
index ff9545780a836b799f672e4c968a99721bac8a8e..9f4629c1b924392a036df8ae4f6ccf75dbc80f7e 100644
--- a/internal/querynode/query_node.go
+++ b/internal/querynode/query_node.go
@@ -445,18 +445,20 @@ func (node *QueryNode) LoadSegments(in *queryPb.LoadSegmentRequest) (*commonpb.S
 	}
 
 	// segments are ordered before LoadSegments calling
-	if in.LastSegmentState.State == commonpb.SegmentState_SegmentGrowing {
-		segmentNum := len(segmentIDs)
-		position := in.LastSegmentState.StartPosition
-		err = node.loadService.seekSegment(position)
-		if err != nil {
-			status := &commonpb.Status{
-				ErrorCode: commonpb.ErrorCode_UNEXPECTED_ERROR,
-				Reason:    err.Error(),
+	for i, state := range in.SegmentStates {
+		if state.State == commonpb.SegmentState_SegmentGrowing {
+			position := state.StartPosition
+			err = node.loadService.seekSegment(position)
+			if err != nil {
+				status := &commonpb.Status{
+					ErrorCode: commonpb.ErrorCode_UNEXPECTED_ERROR,
+					Reason:    err.Error(),
+				}
+				return status, err
 			}
-			return status, err
+			segmentIDs = segmentIDs[:i]
+			break
 		}
-		segmentIDs = segmentIDs[:segmentNum-1]
 	}
 
 	err = node.loadService.loadSegment(collectionID, partitionID, segmentIDs, fieldIDs)
diff --git a/internal/queryservice/meta_replica.go b/internal/queryservice/meta_replica.go
index 2d165ad460a0681feff2b288d58964be3b2225dd..c7c97085a44700dfe085ee9ca7b8c3796d219e5d 100644
--- a/internal/queryservice/meta_replica.go
+++ b/internal/queryservice/meta_replica.go
@@ -13,6 +13,9 @@ type metaReplica interface {
 	loadPartition(dbID UniqueID, collectionID UniqueID, partitionID UniqueID) (*partition, error)
 	updatePartitionState(dbID UniqueID, collectionID UniqueID, partitionID UniqueID, state querypb.PartitionState) error
 	getPartitionStates(dbID UniqueID, collectionID UniqueID, partitionIDs []UniqueID) ([]*querypb.PartitionStates, error)
+	releaseCollection(dbID UniqueID, collectionID UniqueID) error
+	releasePartition(dbID UniqueID, collectionID UniqueID, partitionID UniqueID) error
+	addDmChannels(collectionID UniqueID, channels []string) error
 }
 
 type segment struct {
@@ -26,9 +29,9 @@ type partition struct {
 }
 
 type collection struct {
-	id           UniqueID
-	partitions   map[UniqueID]*partition
-	node2channel map[int][]string
+	id             UniqueID
+	partitions     map[UniqueID]*partition
+	dmChannelNames []string
 }
 
 type metaReplicaImpl struct {
@@ -48,18 +51,18 @@ func newMetaReplica() metaReplica {
 }
 
 func (mp *metaReplicaImpl) addCollection(dbID UniqueID, collectionID UniqueID) (*collection, error) {
+	//TODO:: assert dbID = 0 exist
 	if _, ok := mp.db2collections[dbID]; ok {
 		partitions := make(map[UniqueID]*partition)
-		node2channel := make(map[int][]string)
 		newCollection := &collection{
-			id:           collectionID,
-			partitions:   partitions,
-			node2channel: node2channel,
+			id:         collectionID,
+			partitions: partitions,
 		}
 		mp.db2collections[dbID] = append(mp.db2collections[dbID], newCollection)
 		return newCollection, nil
 	}
-	return nil, errors.New("can't find dbID when add collection")
+
+	return nil, errors.New("addCollection: can't find dbID when add collection")
 }
 
 func (mp *metaReplicaImpl) addPartition(dbID UniqueID, collectionID UniqueID, partitionID UniqueID) (*partition, error) {
@@ -78,7 +81,7 @@ func (mp *metaReplicaImpl) addPartition(dbID UniqueID, collectionID UniqueID, pa
 			}
 		}
 	}
-	return nil, errors.New("can't find collection when add partition")
+	return nil, errors.New("addPartition: can't find collection when add partition")
 }
 
 func (mp *metaReplicaImpl) getCollections(dbID UniqueID) ([]*collection, error) {
@@ -86,7 +89,7 @@ func (mp *metaReplicaImpl) getCollections(dbID UniqueID) ([]*collection, error)
 		return collections, nil
 	}
 
-	return nil, errors.New("can't find collectionID")
+	return nil, errors.New("getCollections: can't find collectionID")
 }
 
 func (mp *metaReplicaImpl) getPartitions(dbID UniqueID, collectionID UniqueID) ([]*partition, error) {
@@ -102,7 +105,7 @@ func (mp *metaReplicaImpl) getPartitions(dbID UniqueID, collectionID UniqueID) (
 		}
 	}
 
-	return nil, errors.New("can't find partitionIDs")
+	return nil, errors.New("getPartitions: can't find partitionIDs")
 }
 
 func (mp *metaReplicaImpl) getSegments(dbID UniqueID, collectionID UniqueID, partitionID UniqueID) ([]*segment, error) {
@@ -119,7 +122,7 @@ func (mp *metaReplicaImpl) getSegments(dbID UniqueID, collectionID UniqueID, par
 			}
 		}
 	}
-	return nil, errors.New("can't find segmentID")
+	return nil, errors.New("getSegments: can't find segmentID")
 }
 
 func (mp *metaReplicaImpl) loadCollection(dbID UniqueID, collectionID UniqueID) (*collection, error) {
@@ -127,14 +130,16 @@ func (mp *metaReplicaImpl) loadCollection(dbID UniqueID, collectionID UniqueID)
 	if collections, err := mp.getCollections(dbID); err == nil {
 		for _, collection := range collections {
 			if collectionID == collection.id {
-				return res, nil
+				res = collection
 			}
 		}
-	} else {
-		res, err = mp.addCollection(dbID, collectionID)
+	}
+	if res == nil {
+		collection, err := mp.addCollection(dbID, collectionID)
 		if err != nil {
 			return nil, err
 		}
+		res = collection
 	}
 	return res, nil
 }
@@ -177,7 +182,7 @@ func (mp *metaReplicaImpl) updatePartitionState(dbID UniqueID,
 			}
 		}
 	}
-	return errors.New("update partition state fail")
+	return errors.New("updatePartitionState: update partition state fail")
 }
 
 func (mp *metaReplicaImpl) getPartitionStates(dbID UniqueID,
@@ -203,3 +208,54 @@ func (mp *metaReplicaImpl) getPartitionStates(dbID UniqueID,
 	}
 	return partitionStates, nil
 }
+
+func (mp *metaReplicaImpl) releaseCollection(dbID UniqueID, collectionID UniqueID) error {
+	if collections, ok := mp.db2collections[dbID]; ok {
+		for i, collection := range collections {
+			if collectionID == collection.id {
+				collections = append(collections[:i], collections[i+1:]...)
+				return nil
+			}
+		}
+	}
+	return errors.New("releaseCollection: can't find dbID or collectionID")
+}
+
+func (mp *metaReplicaImpl) releasePartition(dbID UniqueID, collectionID UniqueID, partitionID UniqueID) error {
+	if collections, ok := mp.db2collections[dbID]; ok {
+		for _, collection := range collections {
+			if collectionID == collection.id {
+				if _, ok := collection.partitions[partitionID]; ok {
+					delete(collection.partitions, partitionID)
+					return nil
+				}
+			}
+		}
+	}
+	return errors.New("releasePartition: can't find dbID or collectionID or partitionID")
+}
+
+func (mp *metaReplicaImpl) addDmChannels(collectionID UniqueID, channels []string) error {
+	//TODO :: use dbID
+	if collections, ok := mp.db2collections[0]; ok {
+		for _, collection := range collections {
+			if collectionID == collection.id {
+				dmChannels := collection.dmChannelNames
+				for _, channel := range channels {
+					match := false
+					for _, existedChannel := range dmChannels {
+						if channel == existedChannel {
+							match = true
+							break
+						}
+					}
+					if !match {
+						dmChannels = append(dmChannels, channel)
+					}
+				}
+				return nil
+			}
+		}
+	}
+	return errors.New("addDmChannels: can't find dbID or collectionID")
+}
diff --git a/internal/queryservice/querynode.go b/internal/queryservice/querynode.go
index bc43fa7c0318233d32a2e149598e1bd710978cdc..46b03fa414fe5c3359cfe671c61bcfc8363413e2 100644
--- a/internal/queryservice/querynode.go
+++ b/internal/queryservice/querynode.go
@@ -8,8 +8,6 @@ import (
 
 type queryNodeInfo struct {
 	client         QueryNodeInterface
-	insertChannels string
-	nodeID         uint64
 	segments       []UniqueID
 	dmChannelNames []string
 }
@@ -25,3 +23,21 @@ func (qn *queryNodeInfo) LoadSegments(in *querypb.LoadSegmentRequest) (*commonpb
 func (qn *queryNodeInfo) GetSegmentInfo(in *querypb.SegmentInfoRequest) (*querypb.SegmentInfoResponse, error) {
 	return qn.client.GetSegmentInfo(in)
 }
+
+func (qn *queryNodeInfo) WatchDmChannels(in *querypb.WatchDmChannelsRequest) (*commonpb.Status, error) {
+	return qn.client.WatchDmChannels(in)
+}
+
+func (qn *queryNodeInfo) AddDmChannels(channels []string) {
+	qn.dmChannelNames = append(qn.dmChannelNames, channels...)
+}
+
+func newQueryNodeInfo(client QueryNodeInterface) *queryNodeInfo {
+	segments := make([]UniqueID, 0)
+	dmChannelNames := make([]string, 0)
+	return &queryNodeInfo{
+		client:         client,
+		segments:       segments,
+		dmChannelNames: dmChannelNames,
+	}
+}
diff --git a/internal/queryservice/queryservice.go b/internal/queryservice/queryservice.go
index 01b60046b105f3aa3cb4a5e286cf206a223ea41d..cb55a836db5f7d81166c46e3732bb3f54be3ad03 100644
--- a/internal/queryservice/queryservice.go
+++ b/internal/queryservice/queryservice.go
@@ -3,7 +3,6 @@ package queryservice
 import (
 	"context"
 	"fmt"
-	"log"
 	"sort"
 	"strconv"
 	"sync/atomic"
@@ -25,6 +24,7 @@ type MasterServiceInterface interface {
 
 type DataServiceInterface interface {
 	GetSegmentStates(req *datapb.SegmentStatesRequest) (*datapb.SegmentStatesResponse, error)
+	GetInsertChannels(req *datapb.InsertChannelRequest) ([]string, error)
 }
 
 type QueryNodeInterface interface {
@@ -47,7 +47,7 @@ type QueryService struct {
 
 	dataServiceClient   DataServiceInterface
 	masterServiceClient MasterServiceInterface
-	queryNodes          []*queryNodeInfo
+	queryNodes          map[UniqueID]*queryNodeInfo
 	numRegisterNode     uint64
 	numQueryChannel     uint64
 
@@ -87,7 +87,7 @@ func (qs *QueryService) GetComponentStates() (*internalpb2.ComponentStates, erro
 		componentStates, err := node.GetComponentStates()
 		if err != nil {
 			subComponentInfos = append(subComponentInfos, &internalpb2.ComponentInfo{
-				NodeID:    int64(nodeID),
+				NodeID:    nodeID,
 				StateCode: internalpb2.StateCode_ABNORMAL,
 			})
 			continue
@@ -111,28 +111,21 @@ func (qs *QueryService) GetStatisticsChannel() (string, error) {
 	return Params.StatsChannelName, nil
 }
 
-// TODO:: do addWatchDmChannel to query node after registerNode
 func (qs *QueryService) RegisterNode(req *querypb.RegisterNodeRequest) (*querypb.RegisterNodeResponse, error) {
 	fmt.Println("register query node =", req.Address)
 	// TODO:: add mutex
-	allocatedID := uint64(len(qs.queryNodes))
+	allocatedID := len(qs.queryNodes)
 
 	registerNodeAddress := req.Address.Ip + ":" + strconv.FormatInt(req.Address.Port, 10)
 	var node *queryNodeInfo
 	if qs.enableGrpc {
 		client := nodeclient.NewClient(registerNodeAddress)
-		node = &queryNodeInfo{
-			client: client,
-			nodeID: allocatedID,
-		}
+		node = newQueryNodeInfo(client)
 	} else {
-		client := querynode.NewQueryNode(qs.loopCtx, allocatedID)
-		node = &queryNodeInfo{
-			client: client,
-			nodeID: allocatedID,
-		}
+		client := querynode.NewQueryNode(qs.loopCtx, uint64(allocatedID))
+		node = newQueryNodeInfo(client)
 	}
-	qs.queryNodes = append(qs.queryNodes, node)
+	qs.queryNodes[UniqueID(allocatedID)] = node
 
 	//TODO::return init params to queryNode
 	return &querypb.RegisterNodeResponse{
@@ -186,10 +179,20 @@ func (qs *QueryService) LoadCollection(req *querypb.LoadCollectionRequest) (*com
 	if err != nil {
 		return fn(err), err
 	}
-	if collection == nil {
+
+	if len(collection.dmChannelNames) != 0 {
 		return fn(nil), nil
 	}
 
+	channelRequest := datapb.InsertChannelRequest{
+		DbID:         req.DbID,
+		CollectionID: req.CollectionID,
+	}
+	dmChannels, err := qs.dataServiceClient.GetInsertChannels(&channelRequest)
+	if err != nil {
+		return fn(err), err
+	}
+
 	// get partitionIDs
 	showPartitionRequest := &milvuspb.ShowPartitionRequest{
 		Base: &commonpb.MsgBase{
@@ -207,6 +210,21 @@ func (qs *QueryService) LoadCollection(req *querypb.LoadCollectionRequest) (*com
 	}
 	partitionIDs := showPartitionResponse.PartitionIDs
 
+	if len(partitionIDs) == 0 {
+		loadSegmentRequest := &querypb.LoadSegmentRequest{
+			CollectionID: collectionID,
+		}
+		for _, node := range qs.queryNodes {
+			_, err := node.LoadSegments(loadSegmentRequest)
+			if err != nil {
+				return fn(err), err
+			}
+		}
+		nodeIDs := qs.shuffleChannelsToQueryNode(dmChannels)
+		err = qs.watchDmChannels(dmChannels, nodeIDs, collection)
+		return fn(err), err
+	}
+
 	loadPartitionsRequest := &querypb.LoadPartitionRequest{
 		Base:         req.Base,
 		DbID:         dbID,
@@ -244,6 +262,14 @@ func (qs *QueryService) ReleaseCollection(req *querypb.ReleaseCollectionRequest)
 
 	status, err := qs.ReleasePartitions(releasePartitionRequest)
 
+	err = qs.replica.releaseCollection(dbID, collectionID)
+	if err != nil {
+		return &commonpb.Status{
+			ErrorCode: commonpb.ErrorCode_UNEXPECTED_ERROR,
+			Reason:    err.Error(),
+		}, err
+	}
+	//TODO:: queryNode cancel subscribe dmChannels
 	return status, err
 }
 
@@ -276,16 +302,40 @@ func (qs *QueryService) LoadPartitions(req *querypb.LoadPartitionRequest) (*comm
 	dbID := req.DbID
 	collectionID := req.CollectionID
 	partitionIDs := req.PartitionIDs
-	qs.replica.loadPartition(dbID, collectionID, partitionIDs[0])
+
 	fn := func(err error) *commonpb.Status {
+		if err != nil {
+			return &commonpb.Status{
+				ErrorCode: commonpb.ErrorCode_UNEXPECTED_ERROR,
+				Reason:    err.Error(),
+			}
+		}
 		return &commonpb.Status{
-			ErrorCode: commonpb.ErrorCode_UNEXPECTED_ERROR,
-			Reason:    err.Error(),
+			ErrorCode: commonpb.ErrorCode_SUCCESS,
 		}
 	}
 
-	// get segments and load segment to query node
+	if len(partitionIDs) == 0 {
+		err := errors.New("partitionIDs are empty")
+		return fn(err), err
+	}
+
+	var collection *collection = nil
+	var err error
+	if collection, err = qs.replica.loadCollection(dbID, collectionID); err != nil {
+		return fn(err), err
+	}
+
 	for _, partitionID := range partitionIDs {
+		partition, err := qs.replica.loadPartition(dbID, collectionID, partitionID)
+		if err != nil {
+			return fn(err), err
+		}
+
+		if partition == nil {
+			return fn(err), nil
+		}
+
 		showSegmentRequest := &milvuspb.ShowSegmentRequest{
 			Base: &commonpb.MsgBase{
 				MsgType: commonpb.MsgType_kShowSegment,
@@ -297,92 +347,110 @@ func (qs *QueryService) LoadPartitions(req *querypb.LoadPartitionRequest) (*comm
 		if err != nil {
 			return fn(err), err
 		}
-		if showSegmentResponse.Status.ErrorCode != commonpb.ErrorCode_SUCCESS {
-			log.Fatal("showSegment fail, v%", showSegmentResponse.Status.Reason)
-		}
+
 		segmentIDs := showSegmentResponse.SegmentIDs
 		segmentStates := make(map[UniqueID]*datapb.SegmentStateInfo)
-		channel2id := make(map[string]int)
-		//id2channels := make(map[int][]string)
-		id2segs := make(map[int][]UniqueID)
-		offset := 0
+		channel2segs := make(map[string][]UniqueID)
 
 		resp, err := qs.dataServiceClient.GetSegmentStates(&datapb.SegmentStatesRequest{
 			SegmentIDs: segmentIDs,
 		})
 
 		if err != nil {
-			log.Fatal("get segment states fail")
+			return fn(err), err
 		}
 
 		for _, state := range resp.States {
 			segmentID := state.SegmentID
 			segmentStates[segmentID] = state
-			var flatChannelName string
-			// channelNames := make([]string, 0)
-			// for i, str := range state.StartPositions {
-			//     flatChannelName += str.ChannelName
-			//     channelNames = append(channelNames, str.ChannelName)
-			//     if i+1 < len(state.StartPositions) {
-			//         flatChannelName += "/"
-			//     }
-			// }
-			if flatChannelName == "" {
-				log.Fatal("segmentState's channel name is empty")
-			}
-			if _, ok := channel2id[flatChannelName]; !ok {
-				channel2id[flatChannelName] = offset
-				//id2channels[offset] = channelNames
-				id2segs[offset] = make([]UniqueID, 0)
-				id2segs[offset] = append(id2segs[offset], segmentID)
-				offset++
+
+			channelName := state.StartPosition.ChannelName
+
+			if _, ok := channel2segs[channelName]; !ok {
+				segments := make([]UniqueID, 0)
+				segments = append(segments, segmentID)
+				channel2segs[channelName] = segments
 			} else {
-				//TODO::check channel name
-				id := channel2id[flatChannelName]
-				id2segs[id] = append(id2segs[id], segmentID)
+				channel2segs[channelName] = append(channel2segs[channelName], segmentID)
 			}
 		}
-		for key, value := range id2segs {
-			sort.Slice(value, func(i, j int) bool { return segmentStates[value[i]].CreateTime < segmentStates[value[j]].CreateTime })
-			selectedSegs := make([]UniqueID, 0)
-			for i, v := range value {
-				if segmentStates[v].State == commonpb.SegmentState_SegmentFlushed {
-					selectedSegs = append(selectedSegs, v)
-				} else {
-					if i > 0 && segmentStates[selectedSegs[i-1]].State != commonpb.SegmentState_SegmentFlushed {
+
+		qs.replica.updatePartitionState(dbID, collectionID, partitionID, querypb.PartitionState_PartialInMemory)
+		for channel, segmentIDs := range channel2segs {
+			sort.Slice(segmentIDs, func(i, j int) bool {
+				return segmentStates[segmentIDs[i]].StartPosition.Timestamp < segmentStates[segmentIDs[j]].StartPosition.Timestamp
+			})
+			var channelLoadDone = false
+			for _, node := range qs.queryNodes {
+				channels2node := node.dmChannelNames
+				for _, ch := range channels2node {
+					if channel == ch {
+						channelLoadDone = true
 						break
 					}
-					selectedSegs = append(selectedSegs, v)
+				}
+				if channelLoadDone {
+					break
+				}
+			}
+			if !channelLoadDone {
+				states := make([]*datapb.SegmentStateInfo, 0)
+				for _, id := range segmentIDs {
+					states = append(states, segmentStates[id])
+				}
+				loadSegmentRequest := &querypb.LoadSegmentRequest{
+					CollectionID:  collectionID,
+					PartitionID:   partitionID,
+					SegmentIDs:    segmentIDs,
+					SegmentStates: states,
+				}
+				dmChannels := []string{channel}
+				nodeIDs := qs.shuffleChannelsToQueryNode(dmChannels)
+				err = qs.watchDmChannels(dmChannels, nodeIDs, collection)
+				if err != nil {
+					return fn(err), err
+				}
+				queryNode := qs.queryNodes[nodeIDs[0]]
+				//TODO:: seek when loadSegment may cause more msgs consumed
+				status, err := queryNode.LoadSegments(loadSegmentRequest)
+				if err != nil {
+					return status, err
 				}
 			}
-			id2segs[key] = selectedSegs
 		}
 
-		qs.replica.updatePartitionState(dbID, collectionID, partitionID, querypb.PartitionState_PartialInMemory)
+		qs.replica.updatePartitionState(dbID, collectionID, partitionID, querypb.PartitionState_InMemory)
+	}
 
-		// TODO:: filter channel for query node
-		for channels, i := range channel2id {
-			for key, node := range qs.queryNodes {
-				if channels == node.insertChannels {
-					statesID := id2segs[i][len(id2segs[i])-1]
-					//TODO :: should be start position
-					// position := segmentStates[statesID-1].StartPositions
-					// segmentStates[statesID].StartPositions = position
-					loadSegmentRequest := &querypb.LoadSegmentRequest{
-						CollectionID:     collectionID,
-						PartitionID:      partitionID,
-						SegmentIDs:       id2segs[i],
-						LastSegmentState: segmentStates[statesID],
-					}
-					status, err := qs.queryNodes[key].LoadSegments(loadSegmentRequest)
-					if err != nil {
-						return status, err
-					}
+	if len(collection.dmChannelNames) == 0 {
+		channelRequest := datapb.InsertChannelRequest{
+			DbID:         dbID,
+			CollectionID: collectionID,
+		}
+
+		dmChannels, err := qs.dataServiceClient.GetInsertChannels(&channelRequest)
+		if err != nil {
+			return fn(err), err
+		}
+		for _, partitionID := range partitionIDs {
+			loadSegmentRequest := &querypb.LoadSegmentRequest{
+				CollectionID: collectionID,
+				PartitionID:  partitionID,
+			}
+			for _, node := range qs.queryNodes {
+				_, err := node.LoadSegments(loadSegmentRequest)
+				if err != nil {
+					return fn(err), nil
 				}
 			}
+			nodeIDs := qs.shuffleChannelsToQueryNode(dmChannels)
+			err = qs.watchDmChannels(dmChannels, nodeIDs, collection)
+		}
+		if err != nil {
+			return fn(err), err
 		}
-		qs.replica.updatePartitionState(dbID, collectionID, partitionID, querypb.PartitionState_InMemory)
 	}
+
 	return &commonpb.Status{
 		ErrorCode: commonpb.ErrorCode_SUCCESS,
 	}, nil
@@ -407,6 +475,13 @@ func (qs *QueryService) ReleasePartitions(req *querypb.ReleasePartitionRequest)
 		}
 
 		segmentIDs = append(segmentIDs, res...)
+		err = qs.replica.releasePartition(dbID, collectionID, partitionID)
+		if err != nil {
+			return &commonpb.Status{
+				ErrorCode: commonpb.ErrorCode_UNEXPECTED_ERROR,
+				Reason:    err.Error(),
+			}, err
+		}
 	}
 	releaseSegmentRequest := &querypb.ReleaseSegmentRequest{
 		Base:         req.Base,
@@ -423,6 +498,7 @@ func (qs *QueryService) ReleasePartitions(req *querypb.ReleasePartitionRequest)
 		}
 	}
 
+	//TODO:: queryNode cancel subscribe dmChannels
 	return &commonpb.Status{
 		ErrorCode: commonpb.ErrorCode_SUCCESS,
 	}, nil
@@ -486,14 +562,14 @@ func (qs *QueryService) GetSegmentInfo(req *querypb.SegmentInfoRequest) (*queryp
 }
 
 func NewQueryService(ctx context.Context) (*QueryService, error) {
-	nodes := make([]*queryNodeInfo, 0)
+	nodes := make(map[UniqueID]*queryNodeInfo)
 	ctx1, cancel := context.WithCancel(ctx)
 	replica := newMetaReplica()
 	service := &QueryService{
 		loopCtx:         ctx1,
 		loopCancel:      cancel,
-		queryNodes:      nodes,
 		replica:         replica,
+		queryNodes:      nodes,
 		numRegisterNode: 0,
 		numQueryChannel: 0,
 		enableGrpc:      false,
@@ -514,3 +590,77 @@ func (qs *QueryService) SetDataService(dataService DataServiceInterface) {
 func (qs *QueryService) SetEnableGrpc(en bool) {
 	qs.enableGrpc = en
 }
+
+func (qs *QueryService) watchDmChannels(dmChannels []string, assignedNodeIDs []UniqueID, collection *collection) error {
+	err := qs.replica.addDmChannels(collection.id, dmChannels)
+	if err != nil {
+		return err
+	}
+	node2channels := make(map[UniqueID][]string)
+	for i, channel := range dmChannels {
+		nodeID := assignedNodeIDs[i]
+		findChannel := false
+		for _, ch := range collection.dmChannelNames {
+			if channel == ch {
+				findChannel = true
+			}
+		}
+		if !findChannel {
+			if _, ok := node2channels[nodeID]; ok {
+				node2channels[nodeID] = append(node2channels[nodeID], channel)
+			} else {
+				channels := make([]string, 0)
+				channels = append(channels, channel)
+				node2channels[nodeID] = channels
+			}
+		}
+	}
+
+	for nodeID, channels := range node2channels {
+		node := qs.queryNodes[nodeID]
+		request := &querypb.WatchDmChannelsRequest{
+			ChannelIDs: channels,
+		}
+		_, err := node.WatchDmChannels(request)
+		node.AddDmChannels(channels)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (qs *QueryService) shuffleChannelsToQueryNode(dmChannels []string) []UniqueID {
+	maxNumDMChannel := 0
+	res := make([]UniqueID, 0)
+	node2lens := make(map[UniqueID]int)
+	for id, node := range qs.queryNodes {
+		node2lens[id] = len(node.dmChannelNames)
+	}
+	offset := 0
+	for {
+		lastOffset := offset
+		for id, len := range node2lens {
+			if len >= maxNumDMChannel {
+				maxNumDMChannel = len
+			} else {
+				res = append(res, id)
+				node2lens[id]++
+				offset++
+			}
+		}
+		if lastOffset == offset {
+			for id := range node2lens {
+				res = append(res, id)
+				node2lens[id]++
+				offset++
+				break
+			}
+		}
+		if offset == len(dmChannels) {
+			break
+		}
+	}
+	return res
+}
diff --git a/internal/queryservice/queryservice_test.go b/internal/queryservice/queryservice_test.go
index e0f26c162f8c08445c5dde019bf423fea9dde2a6..a6e36bbee1c1cddb17b93dd8f30cc539b969ccc1 100644
--- a/internal/queryservice/queryservice_test.go
+++ b/internal/queryservice/queryservice_test.go
@@ -155,6 +155,9 @@ func (data *dataMock) GetSegmentStates(req *datapb.SegmentStatesRequest) (*datap
 
 	return ret, nil
 }
+func (data *dataMock) GetInsertChannels(req *datapb.InsertChannelRequest) ([]string, error) {
+	return []string{"test-insert"}, nil
+}
 
 func TestQueryService_Init(t *testing.T) {
 	service, err := NewQueryService(context.Background())