Monitoring Replication Lag in MySQL

Check Replication Lag

Write a MySQL query to check the replication lag on a slave server.

Solution:

-- Check replication lag
SELECT 
    SEC_TO_TIME(MASTER_POS_WAIT('', 0)) AS replication_lag;

Explanation:

• Purpose of the Query:
• Measures how far behind the slave is compared to the master.
• Key Components:
• MASTER_POS_WAIT function waits for the slave to catch up to the master at a specific position; here, it's used to measure the lag.
• Real-World Application:
• Useful for monitoring performance and ensuring data consistency in real-time scenarios.

Notes:

• A high replication lag might indicate network issues or a backlog of data to process.

For more Practice: Solve these Related Problems:

• Write a MySQL query to calculate the average replication lag over the last hour on a slave.
• Write MySQL to monitor replication lag across multiple slaves using a single query.

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Previous MySQL Exercise: Promote Slave to Master.
Next MySQL Exercise: Multi-Master Replication Setup.