diff --git a/docs/go-version-data-flow.html b/docs/go-version-data-flow.html
index de2b6598..27d738eb 100644
--- a/docs/go-version-data-flow.html
+++ b/docs/go-version-data-flow.html
@@ -408,7 +408,7 @@
           <div class="lane-title">落库与查询</div>
           <div class="node store">
             <strong>history-writer</strong>
-            <p>消费 RAW topic，写 TDengine：raw_frames、payload_chunks、locations、mileage_points。</p>
+            <p>消费 RAW topic，写 TDengine：raw_frames、payload_chunks、locations。</p>
           </div>
           <div class="node store">
             <strong>stat-writer</strong>
diff --git a/go/vehicle-gateway/internal/realtime/snapshot_writer.go b/go/vehicle-gateway/internal/realtime/snapshot_writer.go
index ef7ea7d8..1c27a8dc 100644
--- a/go/vehicle-gateway/internal/realtime/snapshot_writer.go
+++ b/go/vehicle-gateway/internal/realtime/snapshot_writer.go
@@ -41,7 +41,7 @@ func (w *SnapshotWriter) EnsureSchema(ctx context.Context) error {
 	if _, err := w.exec.ExecContext(ctx, realtimeLocationTableSQL); err != nil {
 		return err
 	}
-	return w.dropObsoleteColumns(ctx)
+	return nil
 }
 
 func (w *SnapshotWriter) Update(ctx context.Context, env envelope.FrameEnvelope) error {
@@ -113,126 +113,6 @@ func (w *SnapshotWriter) plateForEnvelope(ctx context.Context, env envelope.Fram
 	return strings.TrimSpace(plate), nil
 }
 
-func (w *SnapshotWriter) dropObsoleteColumns(ctx context.Context) error {
-	queryer, ok := w.exec.(Queryer)
-	if !ok {
-		return nil
-	}
-	if err := w.ensureRealtimeVINIndexes(ctx, queryer); err != nil {
-		return err
-	}
-	for _, column := range []struct {
-		table string
-		name  string
-	}{
-		{table: "vehicle_realtime_snapshot", name: "parsed_json"},
-		{table: "vehicle_realtime_snapshot", name: "fields_json"},
-		{table: "vehicle_realtime_snapshot", name: "vehicle_key"},
-		{table: "vehicle_realtime_snapshot", name: "phone"},
-		{table: "vehicle_realtime_snapshot", name: "device_id"},
-		{table: "vehicle_realtime_snapshot", name: "message_id"},
-		{table: "vehicle_realtime_snapshot", name: "sequence_id"},
-		{table: "vehicle_realtime_snapshot", name: "source_endpoint"},
-		{table: "vehicle_realtime_location", name: "fields_json"},
-		{table: "vehicle_realtime_location", name: "vehicle_key"},
-		{table: "vehicle_realtime_location", name: "phone"},
-		{table: "vehicle_realtime_location", name: "device_id"},
-		{table: "vehicle_realtime_location", name: "message_id"},
-		{table: "vehicle_realtime_location", name: "sequence_id"},
-		{table: "vehicle_realtime_location", name: "source_endpoint"},
-	} {
-		exists, err := columnExists(ctx, queryer, column.table, column.name)
-		if err != nil {
-			return err
-		}
-		if !exists {
-			continue
-		}
-		if _, err := w.exec.ExecContext(ctx, "ALTER TABLE "+column.table+" DROP COLUMN "+column.name); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func (w *SnapshotWriter) ensureRealtimeVINIndexes(ctx context.Context, queryer Queryer) error {
-	for _, item := range []struct {
-		table    string
-		oldIndex string
-		newIndex string
-	}{
-		{table: "vehicle_realtime_snapshot", oldIndex: "uk_realtime_snapshot_vehicle", newIndex: "uk_realtime_snapshot_vin"},
-		{table: "vehicle_realtime_location", oldIndex: "uk_realtime_location_vehicle", newIndex: "uk_realtime_location_vin"},
-	} {
-		if err := w.normalizeVINRows(ctx, item.table); err != nil {
-			return err
-		}
-		exists, err := indexExists(ctx, queryer, item.table, item.newIndex)
-		if err != nil {
-			return err
-		}
-		if !exists {
-			if _, err := w.exec.ExecContext(ctx, "ALTER TABLE "+item.table+" ADD UNIQUE KEY "+item.newIndex+" (protocol, vin)"); err != nil {
-				return err
-			}
-		}
-		exists, err = indexExists(ctx, queryer, item.table, item.oldIndex)
-		if err != nil {
-			return err
-		}
-		if exists {
-			if _, err := w.exec.ExecContext(ctx, "ALTER TABLE "+item.table+" DROP INDEX "+item.oldIndex); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
-
-func (w *SnapshotWriter) normalizeVINRows(ctx context.Context, table string) error {
-	if _, err := w.exec.ExecContext(ctx, "DELETE FROM "+table+" WHERE vin IS NULL OR vin = ''"); err != nil {
-		return err
-	}
-	_, err := w.exec.ExecContext(ctx, `DELETE newer_duplicate
-FROM `+table+` newer_duplicate
-JOIN `+table+` latest
-  ON newer_duplicate.protocol = latest.protocol
- AND newer_duplicate.vin = latest.vin
- AND (
-   newer_duplicate.updated_at < latest.updated_at
-   OR (newer_duplicate.updated_at = latest.updated_at AND newer_duplicate.id < latest.id)
- )`)
-	return err
-}
-
-func columnExists(ctx context.Context, queryer Queryer, table string, column string) (bool, error) {
-	var count int
-	err := queryer.QueryRowContext(ctx, `
-SELECT COUNT(*)
-FROM information_schema.columns
-WHERE table_schema = DATABASE()
-  AND table_name = ?
-  AND column_name = ?`, table, column).Scan(&count)
-	if err != nil {
-		return false, err
-	}
-	return count > 0, nil
-}
-
-func indexExists(ctx context.Context, queryer Queryer, table string, index string) (bool, error) {
-	var count int
-	err := queryer.QueryRowContext(ctx, `
-SELECT COUNT(*)
-FROM information_schema.statistics
-WHERE table_schema = DATABASE()
-  AND table_name = ?
-  AND index_name = ?`, table, index).Scan(&count)
-	if err != nil {
-		return false, err
-	}
-	return count > 0, nil
-}
-
 type realtimeLocationRow struct {
 	Protocol       string
 	VIN            string
diff --git a/go/vehicle-gateway/internal/realtime/snapshot_writer_test.go b/go/vehicle-gateway/internal/realtime/snapshot_writer_test.go
index 0251c7e8..17f66bec 100644
--- a/go/vehicle-gateway/internal/realtime/snapshot_writer_test.go
+++ b/go/vehicle-gateway/internal/realtime/snapshot_writer_test.go
@@ -7,6 +7,8 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/DATA-DOG/go-sqlmock"
+
 	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
 )
 
@@ -79,6 +81,27 @@ func TestSnapshotWriterEnsuresSchemaAndUpsertsCoreSnapshot(t *testing.T) {
 	}
 }
 
+func TestSnapshotWriterEnsureSchemaOnlyCreatesTargetTables(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	writer := NewSnapshotWriter(db)
+
+	mock.ExpectExec("CREATE TABLE IF NOT EXISTS vehicle_realtime_snapshot").
+		WillReturnResult(sqlmock.NewResult(0, 0))
+	mock.ExpectExec("CREATE TABLE IF NOT EXISTS vehicle_realtime_location").
+		WillReturnResult(sqlmock.NewResult(0, 0))
+
+	if err := writer.EnsureSchema(context.Background()); err != nil {
+		t.Fatalf("EnsureSchema() error = %v", err)
+	}
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatalf("unexpected compatibility migration query: %v", err)
+	}
+}
+
 func TestSnapshotWriterUpsertsRealtimeLocationWhenCoordinatesExist(t *testing.T) {
 	exec := &recordingSnapshotExec{}
 	writer := NewSnapshotWriter(exec)