Question: does vitess have a plan to support mgr?

[hustjieke]

Question

Hello, everyone, vitess is an outstanding project and I have been following it for a long time.
I'm interested in adpating MGR into vitess and I see the vtgr had been introduced into vitess in v16 as an experimental properties.
Refs: #13300

I have some questions here, I do many test on failover cases and found vtgr works well.
Further more, what extent does vtgr adapt to vitess in v16? Does it works well with other components? I'm now doing adapting work in my personal feature and I found some work has not done yet like operations on CLI & clustermanager cmds that interact with vttablet RPC interfaces are not suitable directly send to MGR.
e.g. interfaces defined in file: go/vt/vttablet/tabletmanager/rpc_agent.go

// RPCTM defines the interface implemented by the TM for RPCs.
// It is useful for RPC implementations to test their full stack.
type RPCTM interface {
    // RPC calls
...
    StopReplication(ctx context.Context) error


    StopReplicationMinimum(ctx context.Context, position string, waitTime time.Duration) (string, error)


    StartReplication(ctx context.Context, semiSync bool) error
...

For start or stop replication, we know it works well in mysql source-replication HA mode, but in MGR, we know it does through bootstrap, in this case, do we still need StopReplication or StartReplication in MGR or we just skip interfaces like this?

[deepthi]

Thank you for your kind words.
As stated in #13300, VTGR was not being maintained, and not being used by anyone in production, so it has been removed from the latest version of Vitess (v18).
We (the current maintainer team) are not able to provide any support for VTGR usage in past releases. It is not a good idea to explore this in v16 because there is no support, and no upgrade path.
If and when we decide to revisit MySQL Group Replication support in Vitess, instead of adding yet another binary that you need to run, we would almost certainly fold it into VTOrc, which is the cluster management component in Vitess. If you are interested in exploring a potential design for providing Group Replication support in VTOrc, please feel free to propose it in the form of an RFC. For an example RFC, see #6277.