Function select_next_page

server/db.js:297–316

* select_next_page get the next url (page) to crawl

(callback)

 * select_next_page get the next url (page) to crawl
 */
function select_next_page (callback) {
  connect( function () {
    const query = `SELECT next_page, COUNT (next_page) AS c
    FROM logs
    WHERE next_page IS NOT null
    AND next_page NOT IN (
      SELECT url
      FROM logs
      WHERE url IS NOT NULL
    )
    GROUP BY next_page
    ORDER BY c ASC
    LIMIT 1;`;
    // console.log('L82: query:', query);
    PG_CLIENT.query(query, function(error, data) {
      utils.log_error(error, data, new Error().stack);
      return utils.exec_cb(callback, error, data);
    });
  });
}

module.exports = {
  connect: connect,