Adding Nodes to a Galera Cluster

Implement Galera Cluster for MySQL

Write MySQL commands to join a node to an existing Galera Cluster.

Solution:

-- Stop the MySQL service on the new node
-- (This step must be performed outside SQL, e.g., via system commands like 'service mysql stop')

-- Edit my.cnf to include cluster settings:
-- wsrep_provider=/usr/lib/galera/libgalera_smm.so
-- wsrep_cluster_address="gcomm://existing_node1,existing_node2"
-- wsrep_cluster_name="my_cluster"

-- Start the MySQL service with cluster bootstrap:
-- (This step must be performed outside SQL, e.g., 'galera_new_cluster --wsrep_cluster_address="gcomm://"')

-- Once MySQL is running, check cluster status:
SHOW STATUS LIKE 'wsrep_cluster_size';
SHOW STATUS LIKE 'wsrep_cluster_status';

Explanation:

• Purpose of the Query:
• Adds a new node to an existing Galera Cluster, which provides synchronous replication for MySQL.
• Key Components:
• Configuration changes in my.cnf for cluster settings.
• Cluster bootstrap is necessary for the first node or when recovering from a complete cluster shutdown.
• Real-World Application:
• Ensures data consistency across all nodes, beneficial for high availability setups.

Notes:

• Be cautious with node addition to avoid cluster split-brain scenarios.
• Ensure all nodes have identical data before joining unless using state transfer.

For more Practice: Solve these Related Problems:

• Write MySQL commands to add a node to an existing Galera Cluster with state transfer settings.
• Write MySQL to configure a node to join a Galera Cluster with specific flow control settings.

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Previous MySQL Exercise: Check Replication Lag.
Next MySQL Exercise: Monitor Galera Cluster Health.