refactor(go): drop redundant daily mileage vin index

go/vehicle-gateway/internal/stats/daily_metric_test.go

@@ -129,6 +129,9 @@ func TestWriterEnsuresSchemaAndUpsertsDailyMileage(t *testing.T) {
 	if !strings.Contains(exec.calls[0].query, "PRIMARY KEY (vin, stat_date, protocol)") {
 		t.Fatalf("daily mileage table should key by vin/stat_date/protocol: %s", exec.calls[0].query)
 	}
+	if strings.Contains(exec.calls[0].query, "KEY idx_vin (vin)") {
+		t.Fatalf("daily mileage table should not keep redundant vin index covered by the primary key: %s", exec.calls[0].query)
+	}
 	if len(exec.calls) != 2 {
 		t.Fatalf("exec calls = %d", len(exec.calls))
 	}

go/vehicle-gateway/internal/stats/schema.go

@@ -10,7 +10,6 @@ const DailyMileageTableSQL = `CREATE TABLE IF NOT EXISTS vehicle_daily_mileage (
   sample_count BIGINT NOT NULL DEFAULT 0,
   updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
   PRIMARY KEY (vin, stat_date, protocol),
-  KEY idx_vin (vin),
   KEY idx_stat_date (stat_date),
   KEY idx_protocol_date (protocol, stat_date)
 )`