Long-connection - Related information

• Do App like Meituan and Didi have to maintain a long connection with the server?

  if it is not maintained, how to push the message and update the information but if it is maintained, it will take too much socket ...

  Long-connection socket app

  May.23,2022
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b37710-e5e3.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b37710-e5e3.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?