Show Slave Status - Impossible coordinates?

MySQL & MariaDB Percona Server for MySQL 5.7
1

Recently I have a replication node that has errored. I noticed something that I think is impossible, but want to confirm:

The coordinates in the show slave status command seems impossible. Please note both IO and SQL threads are pointing to the same binary log file bin-1.084438. And yet the SQL thread coordinate is higher than the IO thread.

Master_Log_File: bin-1.084438
Read_Master_Log_Pos: 48870187
Relay_Master_Log_File: bin-1.084438
Exec_Master_Log_Pos: 765952106

The exec_master_log_pos is a higher number than read_master_log_pos within the same binary log file. I would think that exec_master_log_pos can never be a higher number when in the same binary log file and at most can be the same number. Unless my logic is wrong it would seem at some point things got really messed up here and the sql thread somehow jumped ahead.

Any thoughts/comments would be appreciated. Perhaps my understanding of binary log position is not correct?

Thanks.

2

Hi, depending on your configuration, the metadata for each thread might be updated every few events (see for example https://dev.mysql.com/doc/refman/8.0/en/replication-options-replica.html#sysvar_sync_master_info) so I guess it is possible to see the IO thread behind the SQL thread. What is the error you are seeing exactly?

3

I have another thread open regarding the error: