skip to balance redundant segment (#23490)

Signed-off-by: Wei Liu <wei.liu@zilliz.com>

internal/querycoordv2/balance/rowcount_based_balancer.go

@@ -152,9 +152,6 @@ func (b *RowCountBasedBalancer) balanceReplica(replica *meta.Replica) ([]Segment
 		}
 	}
 
-	log.Info("balance channel xxxxx",
-		zap.Int64s("online nodes", lo.Keys(onlineNodesSegments)),
-		zap.Int64s("offline nodes", lo.Keys(stoppingNodesSegments)))
 	if len(nodes) == len(stoppingNodesSegments) || len(onlineNodesSegments) == 0 {
 		// no available nodes to balance
 		return nil, nil
@@ -189,6 +186,11 @@ func (b *RowCountBasedBalancer) balanceReplica(replica *meta.Replica) ([]Segment
 		}
 	}
 
+	segmentsToMove = lo.Filter(segmentsToMove, func(s *meta.Segment, _ int) bool {
+		// if the segment are redundant, skip it's balance for now
+		return len(b.dist.SegmentDistManager.Get(s.GetID())) == 1
+	})
+
 	return b.genSegmentPlan(replica, nodesWithLessRow, segmentsToMove, average), b.genChannelPlan(replica, lo.Keys(onlineNodesSegments), lo.Keys(stoppingNodesSegments))
 }
 

internal/querycoordv2/balance/rowcount_based_balancer_test.go

@@ -162,6 +162,21 @@ func (suite *RowCountBasedBalancerTestSuite) TestBalance() {
 			},
 			expectChannelPlans: []ChannelAssignPlan{},
 		},
+		{
+			name:        "skip balance for redundant segment",
+			nodes:       []int64{1, 2},
+			segmentCnts: []int{1, 2},
+			states:      []session.State{session.NodeStateNormal, session.NodeStateNormal},
+			distributions: map[int64][]*meta.Segment{
+				1: {{SegmentInfo: &datapb.SegmentInfo{ID: 1, CollectionID: 1, NumOfRows: 20}, Node: 1}},
+				2: {
+					{SegmentInfo: &datapb.SegmentInfo{ID: 1, CollectionID: 1, NumOfRows: 20}, Node: 2},
+					{SegmentInfo: &datapb.SegmentInfo{ID: 3, CollectionID: 1, NumOfRows: 40}, Node: 2},
+				},
+			},
+			expectPlans:        []SegmentAssignPlan{},
+			expectChannelPlans: []ChannelAssignPlan{},
+		},
 		{
 			name:        "balance won't trigger",
 			nodes:       []int64{1, 2, 3},