July 2019 Summaries

RevenueCat successfully executed a zero-downtime migration of its main PostgreSQL database from Amazon RDS to Aurora to address scalability and performance challenges while maintaining continuous service for its high-throughput system that processes over 600 requests per second. The limitations of RDS, such as the potential for several minutes of downtime during failover and the need for manual IOPS provisioning, prompted the switch to Aurora, which offers faster failover and automatic I/O handling. The migration strategy capitalized on RevenueCat's idempotent SDK endpoints, logging POST requests during the transition to ensure no data loss occurred. By conducting thorough research, testing, and dry runs, the company minimized risks, orchestrating the migration smoothly within five minutes during a period of low traffic, with the entire team ready to support in case of unforeseen issues. This proactive approach, alongside the testing of rollback plans, ensured a seamless upgrade without affecting the service availability for customers, highlighting the importance of deliberate planning and understanding system nuances for such critical operations.

In June, the author had the opportunity to speak at AltConf, a community event held alongside Apple's WWDC, where they discussed building effective subscriptions for iOS apps, a topic initially explored in their blog post titled "iOS Subscriptions are Hard." The talk covered challenges such as price tracking, refreshing, server notifications, and other complexities involved in creating fully-featured support for iOS subscriptions. This presentation aimed to provide a high-level overview of the intricacies and best practices for managing iOS app subscriptions.