fix: [2.4] Querycoord will trigger unexpected balance task after rest…

…art (#38714)

issue: #38606 
pr: #38630

---------

Signed-off-by: Wei Liu <[email protected]>

internal/proto/query_coord.proto

@@ -827,6 +827,7 @@ message CheckerInfo {
 message SegmentTarget {
   int64 ID = 1;
   data.SegmentLevel level = 2; 
+  int64 num_of_rows = 3;
 }
 
 message PartitionTarget {

internal/querycoordv2/checkers/balance_checker.go

@@ -119,6 +119,17 @@ func (b *BalanceChecker) replicasToBalance() []int64 {
 		return nil
 	}
 
+	// Before performing balancing, check the CurrentTarget/LeaderView/Distribution for all collections.
+	// If any collection has unready info, skip the balance operation to avoid inconsistencies.
+	notReadyCollections := lo.Filter(loadedCollections, func(cid int64, _ int) bool {
+		// todo: should also check distribution and leader view in the future
+		return !b.targetMgr.IsCurrentTargetReady(cid)
+	})
+	if len(notReadyCollections) > 0 {
+		log.RatedInfo(10, "skip normal balance, cause collection not ready for balance", zap.Int64s("collectionIDs", notReadyCollections))
+		return nil
+	}
+
 	// iterator one normal collection in one round
 	normalReplicasToBalance := make([]int64, 0)
 	hasUnbalancedCollection := false

internal/querycoordv2/checkers/balance_checker_test.go

@@ -320,20 +320,8 @@ func (suite *BalanceCheckerTestSuite) TestTargetNotReady() {
 	suite.checker.meta.ResourceManager.HandleNodeUp(nodeID1)
 	suite.checker.meta.ResourceManager.HandleNodeUp(nodeID2)
 
-	segments := []*datapb.SegmentInfo{
-		{
-			ID:            1,
-			PartitionID:   1,
-			InsertChannel: "test-insert-channel",
-		},
-	}
-	channels := []*datapb.VchannelInfo{
-		{
-			CollectionID: 1,
-			ChannelName:  "test-insert-channel",
-		},
-	}
-	suite.broker.EXPECT().GetRecoveryInfoV2(mock.Anything, mock.Anything).Return(channels, segments, nil)
+	mockTarget := meta.NewMockTargetManager(suite.T())
+	suite.checker.targetMgr = mockTarget
 
 	// set collections meta
 	cid1, replicaID1, partitionID1 := 1, 1, 1
@@ -343,8 +331,6 @@ func (suite *BalanceCheckerTestSuite) TestTargetNotReady() {
 	partition1 := utils.CreateTestPartition(int64(cid1), int64(partitionID1))
 	suite.checker.meta.CollectionManager.PutCollection(collection1, partition1)
 	suite.checker.meta.ReplicaManager.Put(replica1)
-	suite.targetMgr.UpdateCollectionNextTarget(int64(cid1))
-	suite.targetMgr.UpdateCollectionCurrentTarget(int64(cid1))
 
 	cid2, replicaID2, partitionID2 := 2, 2, 2
 	collection2 := utils.CreateTestCollection(int64(cid2), int32(replicaID2))
@@ -354,6 +340,17 @@ func (suite *BalanceCheckerTestSuite) TestTargetNotReady() {
 	suite.checker.meta.CollectionManager.PutCollection(collection2, partition2)
 	suite.checker.meta.ReplicaManager.Put(replica2)
 
+	// test normal balance when one collection has unready target
+	mockTarget.EXPECT().IsNextTargetExist(mock.Anything).Return(true)
+	mockTarget.EXPECT().IsCurrentTargetReady(mock.Anything).Return(false)
+	replicasToBalance := suite.checker.replicasToBalance()
+	suite.Len(replicasToBalance, 0)
+
+	// test stopping balance with target not ready
+	mockTarget.ExpectedCalls = nil
+	mockTarget.EXPECT().IsNextTargetExist(mock.Anything).Return(false)
+	mockTarget.EXPECT().IsCurrentTargetExist(int64(cid1), mock.Anything).Return(true)
+	mockTarget.EXPECT().IsCurrentTargetExist(int64(cid2), mock.Anything).Return(false)
 	mr1 := replica1.CopyForWrite()
 	mr1.AddRONode(1)
 	suite.checker.meta.ReplicaManager.Put(mr1.IntoReplica())
@@ -362,9 +359,8 @@ func (suite *BalanceCheckerTestSuite) TestTargetNotReady() {
 	mr2.AddRONode(1)
 	suite.checker.meta.ReplicaManager.Put(mr2.IntoReplica())
 
-	// test stopping balance
 	idsToBalance := []int64{int64(replicaID1)}
-	replicasToBalance := suite.checker.replicasToBalance()
+	replicasToBalance = suite.checker.replicasToBalance()
 	suite.ElementsMatch(idsToBalance, replicasToBalance)
 }
 

internal/querycoordv2/meta/target.go

@@ -20,9 +20,11 @@ import (
 	"time"
 
 	"github.com/samber/lo"
+	"go.uber.org/zap"
 
 	"github.com/milvus-io/milvus/internal/proto/datapb"
 	"github.com/milvus-io/milvus/internal/proto/querypb"
+	"github.com/milvus-io/milvus/pkg/log"
 	"github.com/milvus-io/milvus/pkg/util/typeutil"
 )
 
@@ -32,6 +34,9 @@ type CollectionTarget struct {
 	dmChannels map[string]*DmChannel
 	partitions typeutil.Set[int64] // stores target partitions info
 	version    int64
+
+	// record target status, if target has been save before milvus v2.4.19, then the target will lack of segment info.
+	lackSegmentInfo bool
 }
 
 func NewCollectionTarget(segments map[int64]*datapb.SegmentInfo, dmChannels map[string]*DmChannel, partitionIDs []int64) *CollectionTarget {
@@ -48,15 +53,20 @@ func FromPbCollectionTarget(target *querypb.CollectionTarget) *CollectionTarget
 	dmChannels := make(map[string]*DmChannel)
 	var partitions []int64
 
+	lackSegmentInfo := false
 	for _, t := range target.GetChannelTargets() {
 		for _, partition := range t.GetPartitionTargets() {
 			for _, segment := range partition.GetSegments() {
+				if segment.GetNumOfRows() <= 0 {
+					lackSegmentInfo = true
+				}
 				segments[segment.GetID()] = &datapb.SegmentInfo{
 					ID:            segment.GetID(),
 					Level:         segment.GetLevel(),
 					CollectionID:  target.GetCollectionID(),
 					PartitionID:   partition.GetPartitionID(),
 					InsertChannel: t.GetChannelName(),
+					NumOfRows:     segment.GetNumOfRows(),
 				}
 			}
 			partitions = append(partitions, partition.GetPartitionID())
@@ -73,11 +83,16 @@ func FromPbCollectionTarget(target *querypb.CollectionTarget) *CollectionTarget
 		}
 	}
 
+	if lackSegmentInfo {
+		log.Info("target has lack of segment info", zap.Int64("collectionID", target.GetCollectionID()))
+	}
+
 	return &CollectionTarget{
-		segments:   segments,
-		dmChannels: dmChannels,
-		partitions: typeutil.NewSet(partitions...),
-		version:    target.GetVersion(),
+		segments:        segments,
+		dmChannels:      dmChannels,
+		partitions:      typeutil.NewSet(partitions...),
+		version:         target.GetVersion(),
+		lackSegmentInfo: lackSegmentInfo,
 	}
 }
 
@@ -111,8 +126,9 @@ func (p *CollectionTarget) toPbMsg() *querypb.CollectionTarget {
 				}
 
 				partitionTarget.Segments = append(partitionTarget.Segments, &querypb.SegmentTarget{
-					ID:    info.GetID(),
-					Level: info.GetLevel(),
+					ID:        info.GetID(),
+					Level:     info.GetLevel(),
+					NumOfRows: info.GetNumOfRows(),
 				})
 			}
 		}
@@ -157,6 +173,11 @@ func (p *CollectionTarget) IsEmpty() bool {
 	return len(p.dmChannels)+len(p.segments) == 0
 }
 
+// if target is ready, it should have all segment info
+func (p *CollectionTarget) Ready() bool {
+	return !p.lackSegmentInfo
+}
+
 type target struct {
 	// just maintain target at collection level
 	collectionTargetMap map[int64]*CollectionTarget

internal/querycoordv2/meta/target_manager.go

@@ -68,6 +68,7 @@ type TargetManagerInterface interface {
 	SaveCurrentTarget(catalog metastore.QueryCoordCatalog)
 	Recover(catalog metastore.QueryCoordCatalog) error
 	CanSegmentBeMoved(collectionID, segmentID int64) bool
+	IsCurrentTargetReady(collectionID int64) bool
 }
 
 type TargetManager struct {
@@ -631,3 +632,14 @@ func (mgr *TargetManager) CanSegmentBeMoved(collectionID, segmentID int64) bool
 
 	return false
 }
+
+func (mgr *TargetManager) IsCurrentTargetReady(collectionID int64) bool {
+	mgr.rwMutex.RLock()
+	defer mgr.rwMutex.RUnlock()
+	target, ok := mgr.current.collectionTargetMap[collectionID]
+	if !ok {
+		return false
+	}
+
+	return target.Ready()
+}

internal/querycoordv2/meta/target_manager_test.go

@@ -570,11 +570,13 @@ func (suite *TargetManagerSuite) TestRecover() {
 			ID:            11,
 			PartitionID:   1,
 			InsertChannel: "channel-1",
+			NumOfRows:     100,
 		},
 		{
 			ID:            12,
 			PartitionID:   1,
 			InsertChannel: "channel-2",
+			NumOfRows:     100,
 		},
 	}
 
@@ -595,6 +597,10 @@ func (suite *TargetManagerSuite) TestRecover() {
 	suite.Len(target.GetAllDmChannelNames(), 2)
 	suite.Len(target.GetAllSegmentIDs(), 2)
 	suite.Equal(target.GetTargetVersion(), version)
+	for _, segment := range target.GetAllSegments() {
+		suite.Equal(int64(100), segment.GetNumOfRows())
+	}
+	suite.True(target.Ready())
 
 	// after recover, target info should be cleaned up
 	targets, err := suite.catalog.GetCollectionTargets()