How to Efficiently Delete Aging Data from MySQL Tables?

Optimizing Deletion of Aging MySQL Data

Deleting rows that exceed a certain age from MySQL tables is a common task, especially for tables containing transient data such as notifications or high scores. Executing such deletions efficiently is crucial on high-traffic tables to avoid performance bottlenecks.

A common approach is to use a cron job that runs periodically (e.g., hourly) and deletes rows based on a threshold. While effective, this method may introduce delays during high traffic due to simultaneous inserts and deletions.

A more efficient solution is to utilize MySQL's Event system. By creating an Event, you can schedule a task to run automatically on a database interval (e.g., daily). This ensures regular deletion of aging rows without interfering with ongoing database operations.

For instance, to delete notifications older than 30 days from a table called "notifications," consider the following Event query:

CREATE EVENT AutoDeleteOldNotifications
ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 DAY 
ON COMPLETION PRESERVE
DO 
DELETE LOW_PRIORITY FROM databaseName.notifications WHERE datetime < DATE_SUB(NOW(), INTERVAL 30 DAY);

After setting up the Event, it will run every 24 hours and perform the cleanup task. This approach minimizes performance impact, ensures timely data purging, and improves overall database efficiency.

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