Bug #91655 "Handling an Unexpected Halt of a Replication Slave" Documentation is uncertain
Submitted: 16 Jul 2018 8:03 Modified: 16 Jul 2018 8:21
Reporter: Uday Varagani Email Updates:
Status: Duplicate Impact on me:
None 
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:5.7, 8.0 OS:Any
Assigned to: CPU Architecture:Any

[16 Jul 2018 8:03] Uday Varagani 
Description:
In the documentation link given below, single thread replication with below settings is mentioned to survive only a Server(MySQL) crash but not OS. 

Gidd 				= OFF 
relay_log_recovery 		= 1 
relaly_log_info_repository 	= TABLE 

https://dev.mysql.com/doc/refman/5.7/en/replication-solutions-unexpected-slave-halt.html 

With the same settings and sync_relay_log = 1 in addition, multi threaded replication is mentioned to survive Server(MySQL) as well as OS crashes.

No mention of why single threaded replication cant survive an OS crash where the multi threaded replication can with an additional setting sync_relay_log = 1 which can also be configured irrespective of applier thread count.

How to repeat:
NA

Suggested fix:
Update documentation about below things.

1. Why sync_relay_log = 1 doesn't matter in case of single threaded replication.

2. Can single threaded replication be OS crash safe with settings below.   
    Gidd			= OFF 
    relay_log_recovery 		= 1 
    relaly_log_info_repository 	= TABLE 
    sync_relay_log              = 1
[16 Jul 2018 8:14] MySQL Verification Team 
Duplicate of https://bugs.mysql.com/bug.php?id=91654.
[16 Jul 2018 8:21] Uday Varagani 
Hello,

I have marked #91654 as closed. Can you please correct the same and keep any one of these active ?