Monitoring Galera Cluster Node Health

Monitor Galera Cluster Health

Write a SQL query to check the health and status of a Galera Cluster node.

Solution:

-- Check if the node is synced with the cluster
SHOW STATUS LIKE 'wsrep_local_state_comment';

-- Check the number of nodes in the cluster
SHOW STATUS LIKE 'wsrep_cluster_size';

-- Check the replication status
SHOW STATUS LIKE 'wsrep_ready';

-- Check for any replication conflicts
SHOW STATUS LIKE 'wsrep_cert_deps_distance';

Explanation:

• Purpose of the Query:
• Monitors the health and operational status of a node within a Galera Cluster.
• Key Components:
• wsrep_local_state_comment indicates the node's state (like Synced, Donor/Desynced).
• wsrep_cluster_size shows how many nodes are in the cluster.
• wsrep_ready indicates if the node is ready for queries.
• wsrep_cert_deps_distance can indicate potential replication conflicts.
• Real-World Application:
• Essential for maintaining and troubleshooting cluster operations.

Notes:

• Regular monitoring helps in early detection of issues like node isolation or replication stalls.

For more Practice: Solve these Related Problems:

• Write a MySQL query to check if any node in a Galera Cluster is in a non-primary state.
• Write MySQL to monitor the number of pending writes in a Galera Cluster.

Go to:

• MySQL Replication and Clustering Exercises Home. ↩
• MySQL Exercises Home ↩

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