Real-time features make applications feel alive. Supabase makes implementing them surprisingly easy.
What is Supabase Realtime?
Supabase Realtime uses WebSockets to push database changes to connected clients instantly. No polling required.
Use Cases
Live Dashboards - See data update as it changes
Chat Applications - Messages appear instantly
Collaborative Editing - Multiple users, one document
Notifications - Instant alerts for users
Live Feeds - Social media-style updates
How It Works
- Client subscribes to a channel
- Database change occurs
- Supabase broadcasts the change
- Client receives and processes it
Setting Up Subscriptions
Basic subscription pattern:
Subscribe to a table → Listen for changes → Update your UI
You can listen for: - INSERT (new records) - UPDATE (modified records) - DELETE (removed records) - ALL (everything)
Filtering Subscriptions
Don't receive everything: - Filter by column values - Subscribe to specific rows - Use Row Level Security
Performance Considerations
Real-time can be expensive: - Limit active subscriptions - Unsubscribe when not needed - Use filters wisely - Consider hybrid approaches
Building a Live Chat
Step-by-step implementation:
- Create messages table
- Subscribe to new messages
- Display messages in UI
- Send messages (insert)
- Handle presence (who's online)
Presence Features
Track who's online: - User joins channel - Broadcast presence - Display active users - Handle disconnections
Collaborative Features
Build Google Docs-like features: - Track cursor positions - Show who's editing - Merge changes - Handle conflicts
Error Handling
Real-time can disconnect: - Detect connection loss - Attempt reconnection - Queue offline changes - Sync on reconnect
Security
Protect your channels: - Use Row Level Security - Validate on server - Don't trust client data - Audit subscriptions
Testing
Test real-time thoroughly: - Multiple clients - Connection drops - High message volume - Edge cases
Production Checklist
Before going live: - Monitor WebSocket connections - Set up alerts - Plan for scale - Have fallback mechanisms
Real-time features delight users. Supabase makes them accessible to everyone.
