[MDEV-27760] event may non stop replicate in circular semisync setup Created: 2022-02-07  Updated: 2023-11-27  Resolved: 2022-03-22

Status: Closed
Project: MariaDB Server
Component/s: Replication
Affects Version/s: 10.6, 10.7, 10.8
Fix Version/s: 10.6.8, 10.7.4, 10.8.3

Type: Bug Priority: Blocker
Reporter: Andrei Elkin Assignee: Andrei Elkin
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-28292 Allow both --replicate-same-server-id... Closed

 Description   

MDEV-21117 had to relax own events acceptance condition for a case when
a former semisync master server recovers after crash as the semisync slave.
That however admits a possibility for endless event "orbiting" in the semisync circular setup
where the master is also a slave.

As a work-around CHANGE MASTER TO ... ignore_domain_ids=(`own_domain_id`) can do,
where own_domain_id is the value of this_server@@global.gtid_domain_id. The command should be invoked
on every server node of the circle configuration.

Also @@global.gtid_strict_mode = ON blocks any attempt to execute own event; the event circulation would stop, but the slave errors out.

 Comments   
Comment by Andrei Elkin [ 2022-02-11 ]

87f18b0e596 HEAD -> bb-10.6-andrei (forced update)

Comment by Andrei Elkin [ 2022-02-14 ]

serg, salve. There's a commit on bb-10.6-andrei that implements a solution that restores server_id filtering
fully in the non-strict gtid mode (that the reporter complained with). The commit shows that it's safe to rely on the gtid mode strictness rules when slave is in in the strict mode so MDEV-21117 fail-over is still provided
but narrowed down now to this mode.
Could you please review this approach?

Comment by Andrei Elkin [ 2022-02-21 ]

880e92a48ba HEAD -> bb-10.6-andrei (forced update)

carries an updated commit.
I did not say that in the commit message, let me suggest is here, or re-suggest as it seems we touched it on Fri, that in 10.9 the semisync-slave-enabled condition to accept own transactions in the gtid strict mode can be removed.

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