@Override
  public void setFetchSize(int fetchSize) throws SQLException {
    checkConnection("setFetchSize");
    if (fetchSize < 0) {
      throw new SQLException(String.format("fetchSize %d must be >= 0!", fetchSize));
    }
    this.fetchSize = fetchSize == 0 ? Config.DEFAULT_FETCH_SIZE : fetchSize;
  }
There are two kinds of sql here: (1) query sql (2) update sql.

<p>(1) return IoTDBJDBCResultSet or IoTDBNonAlignJDBCResultSet (2) simply get executed
iotdb-client/jdbc/src/main/java/org/apache/iotdb/jdbc/IoTDBStatement.java