What are schemas, roles, sequences, functions and triggers?

Definition:

PostgreSQL schemas organize database objects, and roles with grants control access to those objects. Sequences generate numeric values, functions package executable database logic, and triggers run configured logic in response to events. These features add organization and automation, but hidden trigger behavior can make writes harder to reason about.

Key points:

• Schemas organize database objects; roles and grants control access.

• Sequences generate numbers but may have gaps; UUIDs provide another ID option.

• Functions contain reusable database logic; triggers run automatically for configured events.

• Sequences are not gap-free counters and a rolled-back transaction can still consume a value.

Interview point:

• Describe permissions and implicit database behavior when explaining an application write path.