IM chat how to store offline messages if the other party is not online

IM chat
how to store offline messages if the other person is not online

Mar.04,2021

throw it directly into the library, type a tag (bound with a member) to the chat room to identify the timestamp of its last read, or message id (if message id can be sorted)

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-64f5-1e4c0be-443c4.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e4c0be-443c4.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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