code: @Override
      public Map<String, Object> count(String task) {
          MappingConfig config = rdbMapping.get(task);
          MappingConfig.DbMapping dbMapping = config.getDbMapping();
          String sql = "SELECT COUNT(1) AS cnt FROM " + SyncUtil.getDbTableName(dbMapping);
          Connection conn = null;
          Map<String, Object> res = new LinkedHashMap<>();
          try {
              conn = dataSource.getConnection();
              Util.sqlRS(conn, sql, rs -> {
                  try {
                      if (rs.next()) {
                          Long rowCount = rs.getLong("cnt");
                          res.put("count", rowCount);
                      }
                  } catch (SQLException e) {
                      logger.error(e.getMessage(), e);
                  }
              });
          } catch (SQLException e) {
              logger.error(e.getMessage(), e);
          } finally {
              if (conn != null) {
                  try {
                      conn.close();
                  } catch (SQLException e) {
                      logger.error(e.getMessage(), e);
                  }
              }
          }
          res.put("targetTable", SyncUtil.getDbTableName(dbMapping));
  
          return res;
      }
docs: 获取总数方法
  
  @param task 任务名, 对应配置名
  @return 总数