The Guardian’s Migration from MongoDB to PostgreSQL on Amazon RDS
The Guardian migrated their CMS’s datastore in 2018 from a self-managed MongoDB cluster to PostgreSQL on Amazon RDS for a fully managed solution. The team did an API-based migration without any downtime. Guardian’s in-house CMS – called Composer – which stores articles, blog content, photo galleries and video was originally built on top of MongoDB as a datastore.
This was preceded by a vendor software backed by an Oracle database. This setup had downtimes whenever the schema had to be migrated. As an alternative, the team looked at various NoSQL dbs, and one of the key reasons for choosing MongoDB seems to have been flexibility.
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