Safely Adding NOT NULL Columns to Your Database Tables

Safely Adding NOT NULL Columns to Your Database Tables

摘要

The Database Migrations team is in charge of creating and maintaining all the internal tools for Shopify teams to carry out schema changes safely and with minimal downtime. One of our latest investigations involved using the popular Large Hadron Migrator (LHM) gem to perform schema changes in MySQL databases, after safety-checking that the migrations can be performed without losing any data. In particular, when adding a NOT NULL columns to an existing table.

In this post, I'll share what we learned and our recommendations for doing so to your own database tables.