You can scale by clicking on the Pricing tier. However note that scaling operations currently only support within a service tier. i.e, scaling up/down within Basic and scaling up/down within standard. Ability to scale across service tiers will come soon. /works at Microsoft and the managed PostgreSQL service /
The application should have logic to re-try connections. When you scale, there is a brief moment ~30-45seconds when the app wont be able to connect to the database and then resumes if you re-try connection.
/I work at Microsoft on the managed PostgreSQL service/
How do you accomplish no application downtime if for 45 seconds you can't connect to the database?
In background processes you might get away with retrying connections for a minute but most users will probably consider your site broken if page load time is 45 seconds.