refactor(go): simplify daily mileage storage

2026-07-02 20:01:03 +08:00
parent abc1b9870a
commit 593dc08870
7 changed files with 74 additions and 203 deletions
--- a/docs/architecture/iot-data-platform-principles.md
+++ b/docs/architecture/iot-data-platform-principles.md
@@ -33,7 +33,7 @@ flowchart LR

    HW --> TDRAW["TDengine raw_frames"]
    HW --> TDLOC["TDengine vehicle_locations"]
-    SW --> MYMET["MySQL vehicle_daily_metric"]
+    SW --> MYMET["MySQL vehicle_daily_mileage"]
    RA --> REDIS["Redis realtime-raw"]
    RA --> MYSNAP["MySQL vehicle_realtime_snapshot"]
    RA --> MYLOC["MySQL vehicle_realtime_location"]
@@ -49,7 +49,7 @@ flowchart LR
 | TDengine | `vehicle_locations` | High-volume location history | time, vin, protocol, longitude, latitude, speed, direction, mileage | full parsed JSON |
 | MySQL | `vehicle_realtime_snapshot` | Latest per-protocol vehicle heartbeat | protocol, vin, plate, event time, received time | phone, device, message sequence, parsed JSON |
 | MySQL | `vehicle_realtime_location` | Latest business location cache | vin, plate, location, speed, mileage, SOC, event time | full raw payload and protocol internals |
-| MySQL | `vehicle_daily_metric` | Queryable daily metrics | vin or vehicle key, date, metric key, value, method, source mileage | per-frame raw details |
+| MySQL | `vehicle_daily_mileage` | Queryable daily mileage | vin or vehicle key, date, protocol, daily mileage, source mileage | generic metric key/value rows, per-frame raw details |
 | MySQL | `vehicle_identity_binding` | Manual identity mapping | vin, plate, phone, device id | registration history |
 | MySQL | `jt808_registration` | JT808 registration and auth trace | phone, device id, plate, auth code, vin match state, first/latest seen | GB32960 or MQTT records |
 | Redis | `realtime-raw:{protocol}:{vin}` | Latest full realtime protocol state | merged latest protocol payload | historical data |
--- a/docs/architecture/storage-minimal-contract.md
+++ b/docs/architecture/storage-minimal-contract.md
@@ -23,7 +23,7 @@
 | TDengine | `vehicle_locations` | 时间、VIN/协议标签、经纬度、速度、方向、SOC、总里程等位置核心字段 | 完整协议 JSON、注册鉴权信息 |
 | MySQL | `vehicle_realtime_snapshot` | 每个协议+VIN 的最新事件时间、接收时间、车牌、事件 ID | phone、device、source endpoint、完整 JSON |
 | MySQL | `vehicle_realtime_location` | 每个协议+VIN 的最新位置核心字段 | raw、parsed JSON、消息头内部字段 |
-| MySQL | `vehicle_daily_metric` | 日期、VIN/临时 vehicle key、协议、指标名、指标值、首末总里程、样本数 | 每帧细节、位置点列表 |
+| MySQL | `vehicle_daily_mileage` | 日期、VIN/临时 vehicle key、协议、日里程、首末总里程、样本数 | 泛化 metric key/value、每帧细节、位置点列表 |
 | MySQL | `vehicle_identity_binding` | 人工维护或导入的 VIN、车牌、phone、device_id 映射 | 注册历史 |
 | MySQL | `jt808_registration` | JT808 phone 主键下的注册、鉴权、VIN 匹配状态 | GB32960/MQTT 注册信息 |
 | Redis | `vehicle:realtime-raw:{protocol}:{vin}` | 每协议最新完整 parsed 状态 | 历史数据、统计结果 |
@@ -40,9 +40,10 @@
   - 兼容：raw 查询只选择公共列，不依赖 `fields_json`；旧表保留该列也不影响查询。
   - 生产：ECS TDengine 历史库已在上线前重建，`raw_frames` 不再包含 `fields_json`。

-3. `vehicle_daily_metric` 的 `vehicle_key` 与 `vin` 同时存在。
+3. `vehicle_daily_mileage` 的 `vehicle_key` 与 `vin` 同时存在。
   - 当前保留原因：JT808 可能先用 phone 作为临时 key，后续才绑定 VIN。
   - 收敛方向：业务查询以 VIN 为主；没有 VIN 的数据只用于排查和待绑定，不作为正式车辆指标。
+   - 生产：RDS 已在上线前删除泛化 `vehicle_daily_metric`，改为专用 `vehicle_daily_mileage`。

 ## 字段提升规则

--- a/go/vehicle-gateway/internal/stats/daily_metric.go
+++ b/go/vehicle-gateway/internal/stats/daily_metric.go
@@ -11,11 +11,6 @@ import (
 	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
 )

-const (
-	MetricDailyMileageKM      = "daily_mileage_km"
-	MetricDailyTotalMileageKM = "daily_total_mileage_km"
-)
-
 type Execer interface {
 	ExecContext(context.Context, string, ...any) (sql.Result, error)
 }
@@ -30,8 +25,6 @@ type MetricSample struct {
 	VIN            string
 	Protocol       envelope.Protocol
 	StatDate       string
-	MetricKey      string
-	MetricValue    float64
 	TotalMileageKM float64
 }

@@ -46,12 +39,9 @@ func NewWriter(exec Execer, loc *time.Location) *Writer {
 }

 func (w *Writer) EnsureSchema(ctx context.Context) error {
-	if _, err := w.exec.ExecContext(ctx, DailyMetricTableSQL); err != nil {
+	if _, err := w.exec.ExecContext(ctx, DailyMileageTableSQL); err != nil {
 		return err
 	}
-	if db, ok := w.exec.(metadataDB); ok {
-		return migrateDailyMetricTable(ctx, db)
-	}
 	return nil
 }

@@ -61,13 +51,11 @@ func (w *Writer) Append(ctx context.Context, env envelope.FrameEnvelope) error {
 		return err
 	}
 	for _, sample := range samples {
-		if _, err := w.exec.ExecContext(ctx, upsertDailyMetricSQL,
+		if _, err := w.exec.ExecContext(ctx, upsertDailyMileageSQL,
 			sample.VehicleKey,
 			sample.VIN,
 			sample.StatDate,
 			string(sample.Protocol),
-			sample.MetricKey,
-			sample.MetricValue,
 			sample.TotalMileageKM,
 			sample.TotalMileageKM); err != nil {
 			return err
@@ -100,33 +88,20 @@ func SamplesFromEnvelope(env envelope.FrameEnvelope, loc *time.Location) ([]Metr
 		return nil, errors.New("event or received time is required")
 	}
 	statDate := time.UnixMilli(eventMS).In(loc).Format("2006-01-02")
-	return []MetricSample{
-		{
-			VehicleKey:     vehicleKey,
-			VIN:            vin,
-			Protocol:       env.Protocol,
-			StatDate:       statDate,
-			MetricKey:      MetricDailyMileageKM,
-			MetricValue:    0,
-			TotalMileageKM: totalMileage,
-		},
-		{
-			VehicleKey:     vehicleKey,
-			VIN:            vin,
-			Protocol:       env.Protocol,
-			StatDate:       statDate,
-			MetricKey:      MetricDailyTotalMileageKM,
-			MetricValue:    totalMileage,
-			TotalMileageKM: totalMileage,
-		},
-	}, nil
+	return []MetricSample{{
+		VehicleKey:     vehicleKey,
+		VIN:            vin,
+		Protocol:       env.Protocol,
+		StatDate:       statDate,
+		TotalMileageKM: totalMileage,
+	}}, nil
 }

-const upsertDailyMetricSQL = `
-INSERT INTO vehicle_daily_metric
-  (vehicle_key, vin, stat_date, protocol, metric_key, metric_value, metric_unit,
-   first_total_mileage_km, latest_total_mileage_km, sample_count, calculation_method)
-VALUES (?, ?, ?, ?, ?, ?, 'km', ?, ?, 1, 'TOTAL_MILEAGE_DIFF')
+const upsertDailyMileageSQL = `
+INSERT INTO vehicle_daily_mileage
+  (vehicle_key, vin, stat_date, protocol, daily_mileage_km,
+   first_total_mileage_km, latest_total_mileage_km, sample_count)
+VALUES (?, ?, ?, ?, 0, ?, ?, 1)
 ON DUPLICATE KEY UPDATE
  vin = IF(VALUES(vin) <> '', VALUES(vin), vin),
  first_total_mileage_km = CASE
@@ -139,112 +114,22 @@ ON DUPLICATE KEY UPDATE
      THEN VALUES(latest_total_mileage_km)
    ELSE GREATEST(latest_total_mileage_km, VALUES(latest_total_mileage_km))
  END,
-  metric_value = CASE
-    WHEN metric_key = 'daily_mileage_km'
-      THEN GREATEST(
-             CASE
-               WHEN latest_total_mileage_km IS NULL OR latest_total_mileage_km <= 0
-                 THEN VALUES(latest_total_mileage_km)
-               ELSE latest_total_mileage_km
-             END,
-             VALUES(latest_total_mileage_km)
-           )
-           - CASE
-               WHEN first_total_mileage_km IS NULL OR first_total_mileage_km <= 0
-                 THEN VALUES(first_total_mileage_km)
-               ELSE LEAST(first_total_mileage_km, VALUES(first_total_mileage_km))
-             END
-    WHEN metric_key = 'daily_total_mileage_km'
-      THEN GREATEST(
-             CASE
-               WHEN latest_total_mileage_km IS NULL OR latest_total_mileage_km <= 0
-                 THEN VALUES(latest_total_mileage_km)
-               ELSE latest_total_mileage_km
-             END,
-             VALUES(latest_total_mileage_km)
-           )
-    ELSE VALUES(metric_value)
+  daily_mileage_km = GREATEST(
+    CASE
+      WHEN latest_total_mileage_km IS NULL OR latest_total_mileage_km <= 0
+        THEN VALUES(latest_total_mileage_km)
+      ELSE latest_total_mileage_km
+    END,
+    VALUES(latest_total_mileage_km)
+  ) - CASE
+    WHEN first_total_mileage_km IS NULL OR first_total_mileage_km <= 0
+      THEN VALUES(first_total_mileage_km)
+    ELSE LEAST(first_total_mileage_km, VALUES(first_total_mileage_km))
  END,
  sample_count = sample_count + 1,
  updated_at = CURRENT_TIMESTAMP
 `

-type metadataDB interface {
-	Execer
-	QueryRowContext(context.Context, string, ...any) *sql.Row
-}
-
-func migrateDailyMetricTable(ctx context.Context, db metadataDB) error {
-	columnExists, err := informationSchemaExists(ctx, db, `
-SELECT COUNT(*)
-FROM information_schema.columns
-WHERE table_schema = DATABASE()
-  AND table_name = 'vehicle_daily_metric'
-  AND column_name = 'vehicle_key'`)
-	if err != nil {
-		return err
-	}
-	if !columnExists {
-		if _, err := db.ExecContext(ctx, `ALTER TABLE vehicle_daily_metric ADD COLUMN vehicle_key VARCHAR(96) NOT NULL DEFAULT '' AFTER id`); err != nil {
-			return err
-		}
-	}
-	if _, err := db.ExecContext(ctx, `UPDATE vehicle_daily_metric SET vehicle_key = vin WHERE vehicle_key = ''`); err != nil {
-		return err
-	}
-	vehicleIndexExists, err := informationSchemaExists(ctx, db, `
-SELECT COUNT(*)
-FROM information_schema.statistics
-WHERE table_schema = DATABASE()
-  AND table_name = 'vehicle_daily_metric'
-  AND index_name = 'uk_daily_metric_vehicle'`)
-	if err != nil {
-		return err
-	}
-	if !vehicleIndexExists {
-		if _, err := db.ExecContext(ctx, `ALTER TABLE vehicle_daily_metric ADD UNIQUE KEY uk_daily_metric_vehicle (vehicle_key, stat_date, protocol, metric_key)`); err != nil {
-			return err
-		}
-	}
-	oldIndexExists, err := informationSchemaExists(ctx, db, `
-SELECT COUNT(*)
-FROM information_schema.statistics
-WHERE table_schema = DATABASE()
-  AND table_name = 'vehicle_daily_metric'
-  AND index_name = 'uk_daily_metric'`)
-	if err != nil {
-		return err
-	}
-	if oldIndexExists {
-		if _, err := db.ExecContext(ctx, `ALTER TABLE vehicle_daily_metric DROP INDEX uk_daily_metric`); err != nil {
-			return err
-		}
-	}
-	vinIndexExists, err := informationSchemaExists(ctx, db, `
-SELECT COUNT(*)
-FROM information_schema.statistics
-WHERE table_schema = DATABASE()
-  AND table_name = 'vehicle_daily_metric'
-  AND index_name = 'idx_vin'`)
-	if err != nil {
-		return err
-	}
-	if !vinIndexExists {
-		if _, err := db.ExecContext(ctx, `ALTER TABLE vehicle_daily_metric ADD KEY idx_vin (vin)`); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func informationSchemaExists(ctx context.Context, db metadataDB, query string) (bool, error) {
-	var count int
-	if err := db.QueryRowContext(ctx, query).Scan(&count); err != nil {
-		return false, err
-	}
-	return count > 0, nil
-}
-
 func floatField(env envelope.FrameEnvelope, key string) (float64, bool) {
 	if env.Fields == nil {
 		return 0, false
--- a/go/vehicle-gateway/internal/stats/daily_metric_test.go
+++ b/go/vehicle-gateway/internal/stats/daily_metric_test.go
@@ -10,7 +10,7 @@ import (
 	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
 )

-func TestSamplesFromEnvelopeDerivesDailyMileageAndTotal(t *testing.T) {
+func TestSamplesFromEnvelopeDerivesDailyMileageSample(t *testing.T) {
 	loc := time.FixedZone("Asia/Shanghai", 8*3600)
 	env := envelope.FrameEnvelope{
 		Protocol:    envelope.ProtocolJT808,
@@ -25,17 +25,14 @@ func TestSamplesFromEnvelopeDerivesDailyMileageAndTotal(t *testing.T) {
 	if err != nil {
 		t.Fatalf("SamplesFromEnvelope() error = %v", err)
 	}
-	if len(samples) != 2 {
+	if len(samples) != 1 {
 		t.Fatalf("sample count = %d", len(samples))
 	}
-	if samples[0].MetricKey != MetricDailyMileageKM || samples[0].MetricValue != 0 {
-		t.Fatalf("unexpected daily mileage sample: %#v", samples[0])
-	}
 	if samples[0].VehicleKey != "LNBVIN00000000001" {
 		t.Fatalf("vehicle key = %q", samples[0].VehicleKey)
 	}
-	if samples[1].MetricKey != MetricDailyTotalMileageKM || samples[1].MetricValue != 10241.2 {
-		t.Fatalf("unexpected daily total sample: %#v", samples[1])
+	if samples[0].TotalMileageKM != 10241.2 {
+		t.Fatalf("total mileage = %v", samples[0].TotalMileageKM)
 	}
 	if samples[0].StatDate != "2026-07-01" {
 		t.Fatalf("stat date = %q", samples[0].StatDate)
@@ -55,7 +52,7 @@ func TestSamplesFromEnvelopeUsesVehicleKeyWhenVINIsMissing(t *testing.T) {
 	if err != nil {
 		t.Fatalf("SamplesFromEnvelope() error = %v", err)
 	}
-	if len(samples) != 2 {
+	if len(samples) != 1 {
 		t.Fatalf("sample count = %d", len(samples))
 	}
 	if samples[0].VehicleKey != "JT808:13307811254" {
@@ -110,7 +107,7 @@ func TestSamplesFromEnvelopeSkipsNonPositiveMileage(t *testing.T) {
 	}
 }

-func TestWriterEnsuresSchemaAndUpsertsTwoMetrics(t *testing.T) {
+func TestWriterEnsuresSchemaAndUpsertsDailyMileage(t *testing.T) {
 	exec := &recordingExec{}
 	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))
 	if err := writer.EnsureSchema(context.Background()); err != nil {
@@ -127,18 +124,21 @@ func TestWriterEnsuresSchemaAndUpsertsTwoMetrics(t *testing.T) {
 		t.Fatalf("Append() error = %v", err)
 	}

-	if !strings.Contains(exec.calls[0].query, "CREATE TABLE IF NOT EXISTS vehicle_daily_metric") {
+	if !strings.Contains(exec.calls[0].query, "CREATE TABLE IF NOT EXISTS vehicle_daily_mileage") {
 		t.Fatalf("unexpected schema sql: %s", exec.calls[0].query)
 	}
 	if !strings.Contains(exec.calls[0].query, "vehicle_key") {
 		t.Fatalf("schema should include vehicle_key: %s", exec.calls[0].query)
 	}
-	if len(exec.calls) != 3 {
+	if len(exec.calls) != 2 {
 		t.Fatalf("exec calls = %d", len(exec.calls))
 	}
 	if !strings.Contains(exec.calls[1].query, "ON DUPLICATE KEY UPDATE") {
 		t.Fatalf("unexpected upsert sql: %s", exec.calls[1].query)
 	}
+	if strings.Contains(exec.calls[1].query, "metric_key") || strings.Contains(exec.calls[1].query, "metric_unit") {
+		t.Fatalf("daily mileage upsert should not use generic metric columns: %s", exec.calls[1].query)
+	}
 	if !strings.Contains(exec.calls[1].query, "first_total_mileage_km <= 0") {
 		t.Fatalf("upsert should ignore legacy zero first mileage: %s", exec.calls[1].query)
 	}
--- a/go/vehicle-gateway/internal/stats/query.go
+++ b/go/vehicle-gateway/internal/stats/query.go
@@ -20,7 +20,6 @@ type MetricQuery struct {
 	VehicleKey string
 	VIN        string
 	Protocol   string
-	MetricKey  string
 	DateFrom   string
 	DateTo     string
 	Limit      int
@@ -32,13 +31,10 @@ type MetricRow struct {
 	VIN                  string   `json:"vin"`
 	StatDate             string   `json:"stat_date"`
 	Protocol             string   `json:"protocol"`
-	MetricKey            string   `json:"metric_key"`
-	MetricValue          float64  `json:"metric_value"`
-	MetricUnit           string   `json:"metric_unit"`
+	DailyMileageKM       float64  `json:"daily_mileage_km"`
 	FirstTotalMileageKM  *float64 `json:"first_total_mileage_km,omitempty"`
 	LatestTotalMileageKM *float64 `json:"latest_total_mileage_km,omitempty"`
 	SampleCount          int64    `json:"sample_count"`
-	CalculationMethod    string   `json:"calculation_method"`
 	CreatedAt            string   `json:"created_at"`
 	UpdatedAt            string   `json:"updated_at"`
 }
@@ -76,13 +72,10 @@ func (r *MetricRepository) Query(ctx context.Context, query MetricQuery) ([]Metr
 			&row.VIN,
 			&statDate,
 			&row.Protocol,
-			&row.MetricKey,
-			&row.MetricValue,
-			&row.MetricUnit,
+			&row.DailyMileageKM,
 			&first,
 			&latest,
 			&row.SampleCount,
-			&row.CalculationMethod,
 			&createdAt,
 			&updatedAt,
 		); err != nil {
@@ -124,7 +117,6 @@ func normalizeMetricQuery(query MetricQuery) MetricQuery {
 	query.VehicleKey = strings.TrimSpace(query.VehicleKey)
 	query.VIN = strings.TrimSpace(query.VIN)
 	query.Protocol = strings.ToUpper(strings.TrimSpace(query.Protocol))
-	query.MetricKey = strings.TrimSpace(query.MetricKey)
 	query.DateFrom = strings.TrimSpace(query.DateFrom)
 	query.DateTo = strings.TrimSpace(query.DateTo)
 	if query.Limit <= 0 {
@@ -135,18 +127,18 @@ func normalizeMetricQuery(query MetricQuery) MetricQuery {

 func buildMetricSQL(query MetricQuery) (string, []any) {
 	where, args := buildMetricWhere(query)
-	sqlText := `SELECT vehicle_key, vin, stat_date, protocol, metric_key, metric_value, metric_unit, first_total_mileage_km, latest_total_mileage_km, sample_count, calculation_method, created_at, updated_at FROM vehicle_daily_metric`
+	sqlText := `SELECT vehicle_key, vin, stat_date, protocol, daily_mileage_km, first_total_mileage_km, latest_total_mileage_km, sample_count, created_at, updated_at FROM vehicle_daily_mileage`
 	if len(where) > 0 {
 		sqlText += " WHERE " + strings.Join(where, " AND ")
 	}
-	sqlText += " ORDER BY stat_date DESC, vehicle_key ASC, protocol ASC, metric_key ASC LIMIT ? OFFSET ?"
+	sqlText += " ORDER BY stat_date DESC, vehicle_key ASC, protocol ASC LIMIT ? OFFSET ?"
 	args = append(args, query.Limit, query.Offset)
 	return sqlText, args
 }

 func buildMetricCountSQL(query MetricQuery) (string, []any) {
 	where, args := buildMetricWhere(query)
-	sqlText := `SELECT COUNT(*) FROM vehicle_daily_metric`
+	sqlText := `SELECT COUNT(*) FROM vehicle_daily_mileage`
 	if len(where) > 0 {
 		sqlText += " WHERE " + strings.Join(where, " AND ")
 	}
@@ -169,9 +161,6 @@ func buildMetricWhere(query MetricQuery) ([]string, []any) {
 	if query.Protocol != "" {
 		add("protocol = ?", query.Protocol)
 	}
-	if query.MetricKey != "" {
-		add("metric_key = ?", query.MetricKey)
-	}
 	if query.DateFrom != "" {
 		add("stat_date >= ?", query.DateFrom)
 	}
@@ -239,7 +228,6 @@ func parseMetricQuery(r *http.Request) (MetricQuery, error) {
 		VehicleKey: values.Get("vehicleKey"),
 		VIN:        values.Get("vin"),
 		Protocol:   values.Get("protocol"),
-		MetricKey:  values.Get("metricKey"),
 		DateFrom:   values.Get("dateFrom"),
 		DateTo:     values.Get("dateTo"),
 		Limit:      limit,
--- a/go/vehicle-gateway/internal/stats/query_test.go
+++ b/go/vehicle-gateway/internal/stats/query_test.go
@@ -18,15 +18,15 @@ func TestMetricRepositoryQueriesDailyMetricsWithFilters(t *testing.T) {
 		t.Fatalf("sqlmock.New() error = %v", err)
 	}
 	defer db.Close()
-	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, metric_key, metric_value, metric_unit, first_total_mileage_km, latest_total_mileage_km, sample_count, calculation_method, created_at, updated_at FROM vehicle_daily_metric").
+	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, daily_mileage_km, first_total_mileage_km, latest_total_mileage_km, sample_count, created_at, updated_at FROM vehicle_daily_mileage").
 		WithArgs("LKLG7C4E3NA774736", "JT808", "2026-07-01", "2026-07-01", 20, 0).
 		WillReturnRows(sqlmock.NewRows([]string{
-			"vehicle_key", "vin", "stat_date", "protocol", "metric_key", "metric_value", "metric_unit",
-			"first_total_mileage_km", "latest_total_mileage_km", "sample_count", "calculation_method",
+			"vehicle_key", "vin", "stat_date", "protocol", "daily_mileage_km",
+			"first_total_mileage_km", "latest_total_mileage_km", "sample_count",
 			"created_at", "updated_at",
 		}).AddRow(
-			"LKLG7C4E3NA774736", "LKLG7C4E3NA774736", time.Date(2026, 7, 1, 0, 0, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)), "JT808", MetricDailyTotalMileageKM, 12345.6, "km",
-			12345.6, 12345.6, 13, "TOTAL_MILEAGE_DIFF", time.Date(2026, 7, 1, 22, 49, 11, 0, time.FixedZone("Asia/Shanghai", 8*3600)), time.Date(2026, 7, 1, 23, 9, 36, 0, time.FixedZone("Asia/Shanghai", 8*3600)),
+			"LKLG7C4E3NA774736", "LKLG7C4E3NA774736", time.Date(2026, 7, 1, 0, 0, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)), "JT808", 12.3,
+			12345.6, 12357.9, 13, time.Date(2026, 7, 1, 22, 49, 11, 0, time.FixedZone("Asia/Shanghai", 8*3600)), time.Date(2026, 7, 1, 23, 9, 36, 0, time.FixedZone("Asia/Shanghai", 8*3600)),
 		))

 	repository := NewMetricRepository(db)
@@ -43,7 +43,7 @@ func TestMetricRepositoryQueriesDailyMetricsWithFilters(t *testing.T) {
 	if len(rows) != 1 {
 		t.Fatalf("row count = %d", len(rows))
 	}
-	if rows[0].MetricKey != MetricDailyTotalMileageKM || rows[0].MetricValue != 12345.6 {
+	if rows[0].DailyMileageKM != 12.3 {
 		t.Fatalf("unexpected row: %#v", rows[0])
 	}
 	if rows[0].VehicleKey != "LKLG7C4E3NA774736" {
@@ -63,18 +63,18 @@ func TestMetricHandlerReturnsDailyMetrics(t *testing.T) {
 		t.Fatalf("sqlmock.New() error = %v", err)
 	}
 	defer db.Close()
-	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM vehicle_daily_metric").
+	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM vehicle_daily_mileage").
 		WithArgs("LB9A32A21R0LS1707", "GB32960", "2020-07-01", "2020-07-01").
 		WillReturnRows(sqlmock.NewRows([]string{"total"}).AddRow(42))
-	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, metric_key, metric_value, metric_unit, first_total_mileage_km, latest_total_mileage_km, sample_count, calculation_method, created_at, updated_at FROM vehicle_daily_metric").
+	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, daily_mileage_km, first_total_mileage_km, latest_total_mileage_km, sample_count, created_at, updated_at FROM vehicle_daily_mileage").
 		WithArgs("LB9A32A21R0LS1707", "GB32960", "2020-07-01", "2020-07-01", 50, 0).
 		WillReturnRows(sqlmock.NewRows([]string{
-			"vehicle_key", "vin", "stat_date", "protocol", "metric_key", "metric_value", "metric_unit",
-			"first_total_mileage_km", "latest_total_mileage_km", "sample_count", "calculation_method",
+			"vehicle_key", "vin", "stat_date", "protocol", "daily_mileage_km",
+			"first_total_mileage_km", "latest_total_mileage_km", "sample_count",
 			"created_at", "updated_at",
 		}).AddRow(
-			"LB9A32A21R0LS1707", "LB9A32A21R0LS1707", "2020-07-01", "GB32960", MetricDailyMileageKM, 0.0, "km",
-			53490.9, 53490.9, 3, "TOTAL_MILEAGE_DIFF", "2026-07-01 22:07:58", "2026-07-01 22:28:25",
+			"LB9A32A21R0LS1707", "LB9A32A21R0LS1707", "2020-07-01", "GB32960", 0.0,
+			53490.9, 53490.9, 3, "2026-07-01 22:07:58", "2026-07-01 22:28:25",
 		))

 	handler := NewMetricHandler(NewMetricRepository(db))
@@ -87,7 +87,7 @@ func TestMetricHandlerReturnsDailyMetrics(t *testing.T) {
 		t.Fatalf("status = %d body=%s", response.Code, response.Body.String())
 	}
 	body := response.Body.String()
-	for _, want := range []string{`"vin":"LB9A32A21R0LS1707"`, `"metric_key":"daily_mileage_km"`, `"total":42`} {
+	for _, want := range []string{`"vin":"LB9A32A21R0LS1707"`, `"daily_mileage_km":0`, `"total":42`} {
 		if !strings.Contains(body, want) {
 			t.Fatalf("response missing %s: %s", want, body)
 		}
@@ -103,18 +103,18 @@ func TestMetricHandlerFiltersByVehicleKey(t *testing.T) {
 		t.Fatalf("sqlmock.New() error = %v", err)
 	}
 	defer db.Close()
-	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM vehicle_daily_metric").
+	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM vehicle_daily_mileage").
 		WithArgs("JT808:013307811254", "JT808").
 		WillReturnRows(sqlmock.NewRows([]string{"total"}).AddRow(12))
-	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, metric_key, metric_value, metric_unit, first_total_mileage_km, latest_total_mileage_km, sample_count, calculation_method, created_at, updated_at FROM vehicle_daily_metric").
+	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, daily_mileage_km, first_total_mileage_km, latest_total_mileage_km, sample_count, created_at, updated_at FROM vehicle_daily_mileage").
 		WithArgs("JT808:013307811254", "JT808", 50, 0).
 		WillReturnRows(sqlmock.NewRows([]string{
-			"vehicle_key", "vin", "stat_date", "protocol", "metric_key", "metric_value", "metric_unit",
-			"first_total_mileage_km", "latest_total_mileage_km", "sample_count", "calculation_method",
+			"vehicle_key", "vin", "stat_date", "protocol", "daily_mileage_km",
+			"first_total_mileage_km", "latest_total_mileage_km", "sample_count",
 			"created_at", "updated_at",
 		}).AddRow(
-			"JT808:013307811254", "", "2026-07-02", "JT808", MetricDailyTotalMileageKM, 10985.7, "km",
-			10985.7, 10985.7, 1, "TOTAL_MILEAGE_DIFF", "2026-07-02 00:03:00", "2026-07-02 00:03:00",
+			"JT808:013307811254", "", "2026-07-02", "JT808", 0.0,
+			10985.7, 10985.7, 1, "2026-07-02 00:03:00", "2026-07-02 00:03:00",
 		))

 	handler := NewMetricHandler(NewMetricRepository(db))
@@ -127,7 +127,7 @@ func TestMetricHandlerFiltersByVehicleKey(t *testing.T) {
 		t.Fatalf("status = %d body=%s", response.Code, response.Body.String())
 	}
 	body := response.Body.String()
-	for _, want := range []string{`"vehicle_key":"JT808:013307811254"`, `"vin":""`, `"metric_value":10985.7`} {
+	for _, want := range []string{`"vehicle_key":"JT808:013307811254"`, `"vin":""`, `"daily_mileage_km":0`} {
 		if !strings.Contains(body, want) {
 			t.Fatalf("response missing %s: %s", want, body)
 		}
@@ -143,14 +143,14 @@ func TestMetricHandlerReturnsEmptyItemsArrayWhenNoRows(t *testing.T) {
 		t.Fatalf("sqlmock.New() error = %v", err)
 	}
 	defer db.Close()
-	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM vehicle_daily_metric").
+	mock.ExpectQuery("SELECT COUNT\\(\\*\\) FROM vehicle_daily_mileage").
 		WithArgs("YUTONG_MQTT").
 		WillReturnRows(sqlmock.NewRows([]string{"total"}).AddRow(0))
-	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, metric_key, metric_value, metric_unit, first_total_mileage_km, latest_total_mileage_km, sample_count, calculation_method, created_at, updated_at FROM vehicle_daily_metric").
+	mock.ExpectQuery("SELECT vehicle_key, vin, stat_date, protocol, daily_mileage_km, first_total_mileage_km, latest_total_mileage_km, sample_count, created_at, updated_at FROM vehicle_daily_mileage").
 		WithArgs("YUTONG_MQTT", 50, 0).
 		WillReturnRows(sqlmock.NewRows([]string{
-			"vehicle_key", "vin", "stat_date", "protocol", "metric_key", "metric_value", "metric_unit",
-			"first_total_mileage_km", "latest_total_mileage_km", "sample_count", "calculation_method",
+			"vehicle_key", "vin", "stat_date", "protocol", "daily_mileage_km",
+			"first_total_mileage_km", "latest_total_mileage_km", "sample_count",
 			"created_at", "updated_at",
 		}))

--- a/go/vehicle-gateway/internal/stats/schema.go
+++ b/go/vehicle-gateway/internal/stats/schema.go
@@ -1,22 +1,19 @@
 package stats

-const DailyMetricTableSQL = `CREATE TABLE IF NOT EXISTS vehicle_daily_metric (
+const DailyMileageTableSQL = `CREATE TABLE IF NOT EXISTS vehicle_daily_mileage (
  id BIGINT PRIMARY KEY AUTO_INCREMENT,
  vehicle_key VARCHAR(96) NOT NULL,
  vin VARCHAR(32) NOT NULL DEFAULT '',
  stat_date DATE NOT NULL,
  protocol VARCHAR(32) NOT NULL,
-  metric_key VARCHAR(64) NOT NULL,
-  metric_value DECIMAL(18,3) NOT NULL,
-  metric_unit VARCHAR(16) NOT NULL,
+  daily_mileage_km DECIMAL(18,3) NOT NULL DEFAULT 0,
  first_total_mileage_km DECIMAL(18,3) NULL,
  latest_total_mileage_km DECIMAL(18,3) NULL,
  sample_count BIGINT NOT NULL DEFAULT 0,
-  calculation_method VARCHAR(64) NOT NULL,
  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
-  UNIQUE KEY uk_daily_metric_vehicle (vehicle_key, stat_date, protocol, metric_key),
+  UNIQUE KEY uk_daily_mileage_vehicle (vehicle_key, stat_date, protocol),
  KEY idx_vin (vin),
  KEY idx_stat_date (stat_date),
-  KEY idx_protocol_metric (protocol, metric_key)
+  KEY idx_protocol_date (protocol, stat_date)
 )`