Removing a Node from Galera Cluster

Force a Node to Leave Galera Cluster

Write MySQL commands to safely remove a node from a Galera Cluster.

Solution:

-- Check current status before leaving
SHOW STATUS LIKE 'wsrep_cluster_size';

-- Stop the node from accepting new writes or reads
SET GLOBAL wsrep_on=OFF;

-- Stop MySQL service
-- (This step must be performed outside SQL, e.g., 'service mysql stop')

-- Remove cluster configuration from my.cnf
-- (This step involves editing the configuration file directly)

-- Restart MySQL without Galera
-- (This step must be performed outside SQL, e.g., 'service mysql start')

Explanation:

• Purpose of the Query:
• Properly removes a node from a Galera Cluster to maintain cluster integrity.
• Key Components:
• Disabling wsrep_on prevents new cluster-related operations.
• Configuration changes and service management are done outside SQL.
• Real-World Application:
• Useful for maintenance, upgrades, or when a node is no longer needed in the cluster

Notes:

• Ensure other nodes are aware of the change in cluster size for load balancing.

For more Practice: Solve these Related Problems:

• Write SQL commands to safely remove a node from a Galera Cluster while maintaining data integrity.
• Write SQL to prepare a node for removal from a Galera Cluster by redirecting its traffic.

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Previous MySQL Exercise: Monitor Galera Cluster Health.
Next MySQL Exercise: Configure Semi-Synchronous Replication.