Heroku Postgres offers different tier plans for customers based on the desired level of functionality and database resilience, that is, failover and high availability. If your business needs are typical of an enterprise application or a large distributed system where failures and downtimes are expected but managed, you should consider premium or enterprise-tier plans.
The enterprise and premium-tier plans come bundled with advanced features of high availability for the PostgreSQL database. What it means is that in case of an unexpected database failure, hardware or otherwise, your application database will switch over to a standby database that contains nearly the same data as your primary database. A switch over decreases the probability of a longer downtime and in turn avoids poor or no application response.
The high availability (HA) feature involves creating a standby database for your primary application database that can be used in case...