This article explains the expand and contract pattern used for updating database schemas without downtime. It outlines the step-by-step process of introducing new structures, migrating data, and ensuring system integrity throughout the transition. The approach allows for safe rollbacks if issues arise during the migration.

The article argues that MySQL is declining under Oracle's management, with fewer updates and a lack of community engagement. It highlights the benefits of switching to MariaDB, which maintains an active open-source development model. Users are encouraged to migrate, especially those reliant on open-source principles.

This article details the process of moving specific tables from one PostgreSQL instance to another using logical replication. It covers granting access, copying schema, setting up publications and subscriptions, and handling sequences and indexes to minimize downtime.

Airbnb has rearchitected its key-value store, Mussel, transitioning from v1 to v2 to meet new demands for real-time data handling and scalability. The new architecture addresses challenges such as operational complexity, consistency flexibility, and data governance, while ensuring a smooth migration process with zero data loss. Key features of v2 include dynamic sharding, automated data expiration, and a robust migration pipeline utilizing Kafka for consistency.

A software team faced a critical issue with a primary key limit on their calendar application, which was approaching the maximum value for a signed 32-bit integer. To avoid breaking customer integrations, they implemented a temporary hack by setting the sequence to utilize the negative range of integers, buying them time to transition to a more robust solution while managing technical debt responsibly. Ultimately, the quick decision allowed for a smooth transition and effective communication with customers.

Motion transitioned from CockroachDB to Postgres due to escalating costs and operational challenges, particularly with migrations and ETL processes. The migration revealed better performance with Postgres for many queries, despite some initial advantages of Cockroach’s query planner. The move ultimately streamlined operations and resolved numerous UI and support issues experienced with CockroachDB.