From 6f4abab6c858749e4ff87341f58f440710649581 Mon Sep 17 00:00:00 2001
From: Spade  A <71589810+SpadeA-Tang@users.noreply.github.com>
Date: Tue, 11 Nov 2025 10:31:36 +0800
Subject: [PATCH] fix: nextFieldID does not consider STRUCT (#45437)

issue: https://github.com/milvus-io/milvus/issues/45362

Signed-off-by: SpadeA <tangchenjie1210@gmail.com>
---
 internal/rootcoord/util.go      | 13 +++++++
 internal/rootcoord/util_test.go | 65 +++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/internal/rootcoord/util.go b/internal/rootcoord/util.go
index 5ecfdad762..96cd9a8f1b 100644
--- a/internal/rootcoord/util.go
+++ b/internal/rootcoord/util.go
@@ -571,5 +571,18 @@ func nextFieldID(coll *model.Collection) int64 {
 			maxFieldID = field.FieldID
 		}
 	}
+
+	// Also check StructArrayFields and their sub-fields to avoid ID conflicts
+	for _, structField := range coll.StructArrayFields {
+		if structField.FieldID > maxFieldID {
+			maxFieldID = structField.FieldID
+		}
+		for _, subField := range structField.Fields {
+			if subField.FieldID > maxFieldID {
+				maxFieldID = subField.FieldID
+			}
+		}
+	}
+
 	return maxFieldID + 1
 }
diff --git a/internal/rootcoord/util_test.go b/internal/rootcoord/util_test.go
index e06dec38f1..b6f25d7080 100644
--- a/internal/rootcoord/util_test.go
+++ b/internal/rootcoord/util_test.go
@@ -23,6 +23,7 @@ import (
 
 	"github.com/milvus-io/milvus-proto/go-api/v2/commonpb"
 	"github.com/milvus-io/milvus-proto/go-api/v2/milvuspb"
+	"github.com/milvus-io/milvus/internal/metastore/model"
 	"github.com/milvus-io/milvus/pkg/v2/common"
 	"github.com/milvus-io/milvus/pkg/v2/mq/msgstream"
 	"github.com/milvus-io/milvus/pkg/v2/util/typeutil"
@@ -453,3 +454,67 @@ func TestIsSubsetOfProperties(t *testing.T) {
 		})
 	}
 }
+
+func Test_nextFieldID(t *testing.T) {
+	type args struct {
+		coll *model.Collection
+	}
+	tests := []struct {
+		name string
+		args args
+		want int64
+	}{
+		{
+			name: "collection with max field ID in struct array sub-field",
+			args: args{
+				coll: &model.Collection{
+					Fields: []*model.Field{
+						{FieldID: common.StartOfUserFieldID},
+					},
+					StructArrayFields: []*model.StructArrayField{
+						{
+							FieldID: common.StartOfUserFieldID + 1,
+							Fields: []*model.Field{
+								{FieldID: common.StartOfUserFieldID + 2},
+								{FieldID: common.StartOfUserFieldID + 10},
+							},
+						},
+					},
+				},
+			},
+			want: common.StartOfUserFieldID + 11,
+		},
+		{
+			name: "collection with multiple struct array fields",
+			args: args{
+				coll: &model.Collection{
+					Fields: []*model.Field{
+						{FieldID: common.StartOfUserFieldID},
+					},
+					StructArrayFields: []*model.StructArrayField{
+						{
+							FieldID: common.StartOfUserFieldID + 1,
+							Fields: []*model.Field{
+								{FieldID: common.StartOfUserFieldID + 2},
+							},
+						},
+						{
+							FieldID: common.StartOfUserFieldID + 5,
+							Fields: []*model.Field{
+								{FieldID: common.StartOfUserFieldID + 6},
+								{FieldID: common.StartOfUserFieldID + 7},
+							},
+						},
+					},
+				},
+			},
+			want: common.StartOfUserFieldID + 8,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := nextFieldID(tt.args.coll)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}