Details
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Bug
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Status: Closed (View Workflow)
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Critical
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Resolution: Not a Bug
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10.1.38, 10.2.23, 10.3.14
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None
Description
galera_new_cluster bootstraps a new cluster. However, when this happens, the cluster keeps its old state. For example:
[ec2-user@ip-172-30-0-249 ~]$ sudo galera_new_cluster
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysql -u root
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Welcome to the MariaDB monitor. Commands end with ; or \g.
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Your MariaDB connection id is 8
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Server version: 10.1.38-MariaDB MariaDB Server
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Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
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MariaDB [(none)]> SHOW GLOBAL VARIABLES WHERE Variable_name IN('wsrep_start_position');
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+----------------------+----------------------------------------+
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| Variable_name | Value |
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+----------------------+----------------------------------------+
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| wsrep_start_position | 0d1774c1-2ce4-11e9-9071-fe16986f98a1:6 |
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+----------------------+----------------------------------------+
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1 row in set (0.00 sec)
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MariaDB [(none)]> SHOW GLOBAL STATUS WHERE Variable_name IN('wsrep_cluster_state_uuid', 'wsrep_last_committed');
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+--------------------------+--------------------------------------+
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| Variable_name | Value |
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+--------------------------+--------------------------------------+
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| wsrep_cluster_state_uuid | 0d1774c1-2ce4-11e9-9071-fe16986f98a1 |
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| wsrep_last_committed | 6 |
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+--------------------------+--------------------------------------+
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2 rows in set (0.00 sec)
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MariaDB [(none)]> \q
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Bye
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[ec2-user@ip-172-30-0-249 ~]$ sudo systemctl stop mariadb
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[ec2-user@ip-172-30-0-249 ~]$ sudo galera_new_cluster
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysql -u root
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Welcome to the MariaDB monitor. Commands end with ; or \g.
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Your MariaDB connection id is 8
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Server version: 10.1.38-MariaDB MariaDB Server
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Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
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MariaDB [(none)]> SHOW GLOBAL VARIABLES WHERE Variable_name IN('wsrep_start_position');
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+----------------------+----------------------------------------+
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| Variable_name | Value |
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+----------------------+----------------------------------------+
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| wsrep_start_position | 0d1774c1-2ce4-11e9-9071-fe16986f98a1:6 |
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+----------------------+----------------------------------------+
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1 row in set (0.00 sec)
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MariaDB [(none)]> SHOW GLOBAL STATUS WHERE Variable_name IN('wsrep_cluster_state_uuid', 'wsrep_last_committed');
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+--------------------------+--------------------------------------+
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| Variable_name | Value |
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+--------------------------+--------------------------------------+
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| wsrep_cluster_state_uuid | 0d1774c1-2ce4-11e9-9071-fe16986f98a1 |
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| wsrep_last_committed | 6 |
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+--------------------------+--------------------------------------+
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2 rows in set (0.00 sec)
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MariaDB [(none)]> \q
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Bye
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If it's a "new" cluster, wouldn't it make sense to start with a new UUID and seqno?
galera_new_cluster starts "mysqld --wsrep-new-cluster" using systemd under the hood. I don't believe that this is a systemd or galera_new_cluster problem, because this still happens if you bypass systemd and start "mysqld --wsrep-new-cluster" directly. For example:
[ec2-user@ip-172-30-0-249 ~]$ sudo mysqld --user=mysql --wsrep-new-cluster &
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[1] 4753
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2019-05-02 17:16:42 140682328529088 [Note] mysqld (mysqld 10.1.39-MariaDB) starting as process 4754 ...
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysql -u root
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Welcome to the MariaDB monitor. Commands end with ; or \g.
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Your MariaDB connection id is 8
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Server version: 10.1.39-MariaDB MariaDB Server
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Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
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MariaDB [(none)]> SHOW GLOBAL VARIABLES WHERE Variable_name IN('wsrep_start_position');
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+----------------------+-----------------------------------------+
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| Variable_name | Value |
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+----------------------+-----------------------------------------+
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| wsrep_start_position | 00000000-0000-0000-0000-000000000000:-1 |
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+----------------------+-----------------------------------------+
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1 row in set (0.00 sec)
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MariaDB [(none)]> SHOW GLOBAL STATUS WHERE Variable_name IN('wsrep_cluster_state_uuid', 'wsrep_last_committed');
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+--------------------------+--------------------------------------+
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| Variable_name | Value |
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+--------------------------+--------------------------------------+
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| wsrep_cluster_state_uuid | 22f991fd-6d1f-11e9-ac6a-b392983e8673 |
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| wsrep_last_committed | 0 |
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+--------------------------+--------------------------------------+
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2 rows in set (0.01 sec)
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MariaDB [(none)]> \q
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Bye
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysqladmin -u root shutdown
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[1]+ Done sudo mysqld -u mysql --wsrep-new-cluster
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysqld --user=mysql --wsrep-new-cluster &
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[1] 4799
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2019-05-02 17:18:15 140331403352256 [Note] mysqld (mysqld 10.1.39-MariaDB) starting as process 4800 ...
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysql -u root
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Welcome to the MariaDB monitor. Commands end with ; or \g.
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Your MariaDB connection id is 8
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Server version: 10.1.39-MariaDB MariaDB Server
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Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
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MariaDB [(none)]> SHOW GLOBAL VARIABLES WHERE Variable_name IN('wsrep_start_position');
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+----------------------+-----------------------------------------+
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| Variable_name | Value |
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+----------------------+-----------------------------------------+
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| wsrep_start_position | 00000000-0000-0000-0000-000000000000:-1 |
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+----------------------+-----------------------------------------+
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1 row in set (0.00 sec)
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MariaDB [(none)]> SHOW GLOBAL STATUS WHERE Variable_name IN('wsrep_cluster_state_uuid', 'wsrep_last_committed');
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+--------------------------+--------------------------------------+
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| Variable_name | Value |
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+--------------------------+--------------------------------------+
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| wsrep_cluster_state_uuid | 22f991fd-6d1f-11e9-ac6a-b392983e8673 |
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| wsrep_last_committed | 0 |
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+--------------------------+--------------------------------------+
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2 rows in set (0.01 sec)
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MariaDB [(none)]> \q
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Bye
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysqladmin -u root shutdown
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[1]+ Done sudo mysqld -u mysql --wsrep-new-cluster
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In order to reset 'wsrep_cluster_state_uuid' and 'wsrep_last_committed', you have to manually delete grastate.dat:
[ec2-user@ip-172-30-0-249 ~]$ sudo galera_new_cluster
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysql -u root
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Welcome to the MariaDB monitor. Commands end with ; or \g.
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Your MariaDB connection id is 9
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Server version: 10.1.38-MariaDB MariaDB Server
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Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
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MariaDB [(none)]> SHOW GLOBAL VARIABLES WHERE Variable_name IN('wsrep_start_position');
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+----------------------+----------------------------------------+
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| Variable_name | Value |
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+----------------------+----------------------------------------+
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| wsrep_start_position | 0d1774c1-2ce4-11e9-9071-fe16986f98a1:6 |
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+----------------------+----------------------------------------+
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1 row in set (0.00 sec)
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MariaDB [(none)]> SHOW GLOBAL STATUS WHERE Variable_name IN('wsrep_cluster_state_uuid', 'wsrep_last_committed');
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+--------------------------+--------------------------------------+
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| Variable_name | Value |
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+--------------------------+--------------------------------------+
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| wsrep_cluster_state_uuid | 0d1774c1-2ce4-11e9-9071-fe16986f98a1 |
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| wsrep_last_committed | 6 |
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+--------------------------+--------------------------------------+
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2 rows in set (0.00 sec)
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MariaDB [(none)]> \q
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Bye
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[ec2-user@ip-172-30-0-249 ~]$ sudo systemctl stop mariadb
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[ec2-user@ip-172-30-0-249 ~]$ sudo rm /var/lib/mysql/grastate.dat
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[ec2-user@ip-172-30-0-249 ~]$ sudo galera_new_cluster
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[ec2-user@ip-172-30-0-249 ~]$ sudo mysql -u root
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Welcome to the MariaDB monitor. Commands end with ; or \g.
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Your MariaDB connection id is 8
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Server version: 10.1.38-MariaDB MariaDB Server
|
|
|
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
|
|
|
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
|
|
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MariaDB [(none)]> SHOW GLOBAL VARIABLES WHERE Variable_name IN('wsrep_start_position');
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+----------------------+----------------------------------------+
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| Variable_name | Value |
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+----------------------+----------------------------------------+
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| wsrep_start_position | 0d1774c1-2ce4-11e9-9071-fe16986f98a1:6 |
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+----------------------+----------------------------------------+
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1 row in set (0.00 sec)
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MariaDB [(none)]> SHOW GLOBAL STATUS WHERE Variable_name IN('wsrep_cluster_state_uuid', 'wsrep_last_committed');
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+--------------------------+--------------------------------------+
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| Variable_name | Value |
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+--------------------------+--------------------------------------+
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| wsrep_cluster_state_uuid | 1ff475b4-57d2-11e9-80ac-077936e51cdd |
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| wsrep_last_committed | 0 |
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+--------------------------+--------------------------------------+
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2 rows in set (0.00 sec)
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MariaDB [(none)]> \q
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Bye
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You can see from above that wsrep_start_position is still not reset when mysqld is started with systemd. This is because MariaDB's systemd unit file has an ExecStartPre option defined that recovers this position using the galera_recovery wrapper script:
https://github.com/MariaDB/server/blob/mariadb-10.1.39/support-files/mariadb.service.in#L72
https://github.com/MariaDB/server/blob/mariadb-10.1.39/scripts/galera_recovery.sh
Attachments
Issue Links
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- Closed
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