Description:
Hi,
the functions MASTER_POS_WAIT, WAIT_FOR_EXECUTED_GTID_SET and WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS allow waiting for the SQL Thread to reach a certain position, but there are no corresponding functions for the IO Thread. In the same logic, START SLAVE UNTIL allows starting replication until the SQL Thread reaches a specific position, but there is no corresponding command for the IO Thread. It would be good to have such functions and command. A use case for those is presented in [1].
[1]: https://jfg-mysql.blogspot.com/2019/07/master-replication-crash-safety-part-4-benchmarks-u...
Many thanks for looking into that,
JFG
How to repeat:
Not a bug, but a feature request, so does not apply.
Suggested fix:
Add functions and commands for:
1) waiting for the IO Thread to reach a binary log position (the name could be MASTER_IO_POS_WAIT)
2) waiting for the IO Thread to have downloaded a list of GTIDs (the name could be WAIT_FOR_RETRIEVED_GTID_SET in reference to Retrieved_Gtid_Set from SHOW SLAVE STATUS)
3) corresponding function of #2 for a specific channel: waiting for a specific channel IO Thread to have downloaded a list of GTIDs (the name could be WAIT_UNTIL_IO_THREAD_AFTER_GTIDS)
4) implementing START SLAVE UNTIL IO_THREAD [...].
At the same time, maybe standardise the naming of those functions and commands and add warnings to the old commands that should be deprecated.
