Data Migration, Backfill, and Reconciliation
A focused chapter on data migration, backfill, and reconciliation, with practical delivery concerns, trade-offs, and the operational questions behind CI/CD work.
Why Data Migration Feels Different From Application Deployment
You have your CI/CD pipeline running smoothly. Application deployments are routine. Rolling updates, blue-green deployments, even canary releases—your
Writing Database Migrations That Won't Break When Run Twice
You're deploying a new feature that needs an extra column in the users table. You write the migration script, run it in staging, everything looks good
Why You Should Always Dry-Run Database Migrations Before Touching Real Data
You have written a migration script. It looks correct. The logic is sound. You run it on staging, and everything passes. But when you run it on
Backfilling Legacy Data Without Breaking Your Production Database
You just deployed a new migration that adds a lastloginat column to the user table. The schema change went smoothly. But now you look at the data: every
Data Reconciliation: Proving Your Migration Worked Correctly
You just finished a data migration. The script ran without errors. The logs look clean. The team is ready to move on. But deep down, you have that nagging
When Data Migration Goes Wrong: Rollback Strategies That Actually Work
You have just deployed a database migration to production. The script ran for twelve minutes, altered three tables, moved data between columns, and then
When Database Migrations Need Their Own Pipeline
You have a solid CI/CD pipeline for your application. Code gets built, tests run, and deployments happen automatically. Then someone opens a pull request