MySQL Bugs: #99345: Group replication consistency error when add instance BUG#30394258 not fixed

Bug #99345	Group replication consistency error when add instance BUG#30394258 not fixed
Submitted:	24 Apr 2020 9:03	Modified:	13 May 2020 9:50
Reporter:	Adrien Girardeau	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Group Replication	Severity:	S2 (Serious)
Version:	8.0.19	OS:	Oracle Linux (Official Docker Image : mysql/mysql-server:8.0.19)
Assigned to:		CPU Architecture:	x86
Tags:	docker, GROUP, InnoDB Cluster, replication

Description:
Hi,

When I add a new instance to the cluster with the command : cluster.addInstance({user: 'root', password: '<password>', host: '172.24.0.44'}, {'recoveryMethod': 'clone'});
I get : "BUG#30394258 – CLUSTER.ADD_INSTANCE: THE OPTION GROUP_REPLICATION_CONSISTENCY CANNOT BE USED".

My cluster has an AFTER group replication consistency.

Which means eventhough the bug is said to be fixed (for example here : https://discordapp.com/channels/@me/690490497441071124/703161279853887529) it is not.

The feature to live adjust the number of instances is really important for me and I can only work with AFTER.

How to repeat:
Setup a InnoDB cluster with some data.

Set the cluster group replication consistency to "AFTER"

Add a new instance to the cluster with a command like : cluster.addInstance({user: 'root', password: '<password>', host: '172.24.0.44'}, {'recoveryMethod': 'clone'});

Enjoy this wonderful error message : BUG#30394258 – CLUSTER.ADD_INSTANCE: THE OPTION GROUP_REPLICATION_CONSISTENCY CANNOT BE USED

The real error message from the server is : 

[ERROR] [MY-013464] [Repl] Plugin group_replication reported: 'There was an issue when configuring the remote cloning process: Error while checking the clone plugin status:  Error number: 3796 Error message: The option group_replication_consistency cannot be used on the current member state.'

The example link is not discord but : https://mysqlserverteam.com/mysql-shell-adminapi-whats-new-in-8-0-19/

Sorry about that.

Hi Adrien,

Thanks for the report. I verified this behavior. Can't say if this is a limitation or a bug, but as it's not listed in limitation...

all best
Bogdan

Posted by developer:
 
Changelog entry added for MySQL 8.0.21:

A global value that is set for the group_replication_consistency system variable, which controls all user connections, is applied on Group Replication's internal connections to MySQL Server modules using the SQL API, which are handled in a similar way to user connections. This could sometimes lead to Group Replication reporting the use of group_replication_consistency as an error, for example when checking the clone plugin status during distributed recovery. Group Replication's internal connections using the SQL API are now configured to use the consistency level EVENTUAL, which matches the behavior before the group_replication_consistency option was available, and does not cause an error message.