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Cloud SQL Migration

1 post · Aug 2026

What this trail covers

Glean has migrated 150 Cloud SQL instances from MySQL 5 to MySQL 8 using GCP DMS. This migration was motivated by MySQL 8's JSON improvements, aiming to speed up operations involving JSON columns. The process involved creating new MySQL 8 instances, copying large datasets (TBs), ensuring source DB availability, and managing service restarts/redeploys. An Asynchronous Upgrade Framework was developed to manage the large scale and duration of these migrations, using a state machine stored in GCS. The framework ensures idempotent operations and allows for state transitions based on replication lag and system load. Early indications show gains in CPU utilization and lower disk I/O with MySQL 8.

All Glean trails
  1. How we migrated 150 Cloud SQL instances using GCP DMSThis post details the migration of 150 Cloud SQL instances from MySQL 5 to MySQL 8 using GCP DMS. It highlights the motivation for the upgrade (JSON improvements in MySQL 8), the main challenges (data copying, source DB availability, service restarts/redeploys), and the solution implemented: GCP DMS with continuous migration jobs. A key contribution is the development of an Asynchronous Upgrade Framework, a state machine stored in GCS, to manage large-scale, long-duration upgrades. The framework ensures idempotent operations and handles state transitions based on replication lag and system load. Early performance gains with MySQL 8 are also noted, including improved CPU utilization and reduced disk I/O.