Database / Supabase Intermediate to Advanced Interview Questions

What is the difference between LISTEN/NOTIFY and Supabase Realtime's Postgres Changes channel?

LISTEN/NOTIFY is a raw Postgres primitive: a connected client issues LISTEN channel_name and then receives any message another session sends via NOTIFY channel_name, 'payload', over that same direct Postgres connection — it requires holding a persistent database connection and has no built-in authorization model.

Supabase Realtime's Postgres Changes channel is built on top of logical replication (not LISTEN/NOTIFY) and is designed for browser and mobile clients: it delivers change events over WebSockets, integrates with Row Level Security so a client only receives events for rows it's allowed to see, and doesn't require the client to hold a raw database connection at all. LISTEN/NOTIFY remains more suited to backend-to-backend signaling within trusted server processes, while Realtime is the client-facing, authorization-aware option.

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What does Supabase Realtime's Postgres Changes channel integrate with that raw LISTEN/NOTIFY does not? Row Level Security, so clients only see authorized events

✓ Correct! Well done.

A local file system cache

✗ Try again, that's not it.

The Storage bucket system

✗ Try again, that's not it.

A separate NoSQL database

✗ Try again, that's not it.

What is LISTEN/NOTIFY still well suited for? Replacing Row Level Security entirely

✗ Try again, that's not it.

Backend-to-backend signaling within trusted server processes

✓ Correct! Well done.

Delivering authorized events directly to a public mobile app

✗ Try again, that's not it.

Resizing images in Storage

✗ Try again, that's not it.

More Related questions...

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