Talk: SaaS on Rails on PostgreSQL

[andyatkinson]

This PR has code samples and examples from the Posette Conf talk "Saas on Rails on PostgreSQL"

https://www.citusdata.com/posette/speakers/andrew-atkinson/

Some of the tech examples:

• Row Level Security
• Composite primary keys
• Active Record Horizontal Sharding
• Citus, row-based and schema-based sharding

[Dandush03]

you should checkout PgRLS it probably solve this by just creating a RLS table and passing the tenant, but i would never recommend adding a RLS implementation for CACHE, just an extra layer of logic, i would recommend using DB sharding for cache