skip balance on loading collection (#20507)

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

internal/querycoordv2/balance/rowcount_based_balancer.go

@@ -19,9 +19,11 @@ package balance
 import (
 	"sort"
 
+	"github.com/milvus-io/milvus/internal/proto/querypb"
 	"github.com/milvus-io/milvus/internal/querycoordv2/meta"
 	"github.com/milvus-io/milvus/internal/querycoordv2/session"
 	"github.com/milvus-io/milvus/internal/querycoordv2/task"
+	"github.com/samber/lo"
 )
 
 type RowCountBasedBalancer struct {
@@ -81,8 +83,13 @@ func (b *RowCountBasedBalancer) convertToNodeItems(nodeIDs []int64) []*nodeItem
 func (b *RowCountBasedBalancer) Balance() ([]SegmentAssignPlan, []ChannelAssignPlan) {
 	ids := b.meta.CollectionManager.GetAll()
 
+	// loading collection should skip balance
+	loadedCollections := lo.Filter(ids, func(cid int64, _ int) bool {
+		return b.meta.GetStatus(cid) == querypb.LoadStatus_Loaded
+	})
+
 	segmentPlans, channelPlans := make([]SegmentAssignPlan, 0), make([]ChannelAssignPlan, 0)
-	for _, cid := range ids {
+	for _, cid := range loadedCollections {
 		replicas := b.meta.ReplicaManager.GetByCollection(cid)
 		for _, replica := range replicas {
 			splans, cplans := b.balanceReplica(replica)

internal/querycoordv2/balance/rowcount_based_balancer_test.go

@@ -21,6 +21,7 @@ import (
 
 	etcdkv "github.com/milvus-io/milvus/internal/kv/etcd"
 	"github.com/milvus-io/milvus/internal/proto/datapb"
+	"github.com/milvus-io/milvus/internal/proto/querypb"
 	"github.com/milvus-io/milvus/internal/querycoordv2/meta"
 	. "github.com/milvus-io/milvus/internal/querycoordv2/params"
 	"github.com/milvus-io/milvus/internal/querycoordv2/session"
@@ -144,7 +145,52 @@ func (suite *RowCountBasedBalancerTestSuite) TestBalance() {
 			suite.SetupSuite()
 			defer suite.TearDownTest()
 			balancer := suite.balancer
-			balancer.meta.CollectionManager.PutCollection(utils.CreateTestCollection(1, 1))
+			collection := utils.CreateTestCollection(1, 1)
+			collection.LoadPercentage = 100
+			collection.Status = querypb.LoadStatus_Loaded
+			balancer.meta.CollectionManager.PutCollection(collection)
+			balancer.meta.ReplicaManager.Put(utils.CreateTestReplica(1, 1, c.nodes))
+			for node, s := range c.distributions {
+				balancer.dist.SegmentDistManager.Update(node, s...)
+			}
+			segmentPlans, channelPlans := balancer.Balance()
+			suite.Empty(channelPlans)
+			suite.ElementsMatch(c.expectPlans, segmentPlans)
+		})
+	}
+
+}
+
+func (suite *RowCountBasedBalancerTestSuite) TestBalanceOnLoadingCollection() {
+	cases := []struct {
+		name          string
+		nodes         []int64
+		distributions map[int64][]*meta.Segment
+		expectPlans   []SegmentAssignPlan
+	}{
+		{
+			name:  "normal balance",
+			nodes: []int64{1, 2},
+			distributions: map[int64][]*meta.Segment{
+				1: {{SegmentInfo: &datapb.SegmentInfo{ID: 1, CollectionID: 1, NumOfRows: 10}, Node: 1}},
+				2: {
+					{SegmentInfo: &datapb.SegmentInfo{ID: 2, CollectionID: 1, NumOfRows: 20}, Node: 2},
+					{SegmentInfo: &datapb.SegmentInfo{ID: 3, CollectionID: 1, NumOfRows: 30}, Node: 2},
+				},
+			},
+			expectPlans: []SegmentAssignPlan{},
+		},
+	}
+
+	for _, c := range cases {
+		suite.Run(c.name, func() {
+			suite.SetupSuite()
+			defer suite.TearDownTest()
+			balancer := suite.balancer
+			collection := utils.CreateTestCollection(1, 1)
+			collection.LoadPercentage = 100
+			collection.Status = querypb.LoadStatus_Loading
+			balancer.meta.CollectionManager.PutCollection(collection)
 			balancer.meta.ReplicaManager.Put(utils.CreateTestReplica(1, 1, c.nodes))
 			for node, s := range c.distributions {
 				balancer.dist.SegmentDistManager.Update(node, s...)