Rails at Scale
Posts
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Rails's Swappable Migration Backend for Schema Changes at Scale
This post explores Rails’s swappable migration backend, a little-known feature that lets applications customize how migrations run. At Shopify, we relied on monkey patches and a brittle SQL parser to make Rails migrations work with our Schema Migrations Service. We developed the swappable backend feature to more simply adapt Rails’s migration runner to our needs. We’ll cover why and how we built this, and how Shopify uses it to power database migrations at scale.
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How We Scaled Maintenance Tasks to Shopify's Core Monolith
In 2020, we built the maintenance_tasks gem as a solution for performing data migrations in Rails applications. Adopting the gem in Shopify’s core Rails monolith was not so simple, however! We had to adapt the gem to fit Core’s sharded architecture and to handle data migrations across millions of rows. Let’s take a look at how we did it.