Build fluency in Supabase's Broadcast, Presence, and Postgres Changes realtime features.
0 / 5 completed
1 / 5
At standup, a dev wants clients to receive live notifications on a shared topic without database changes. Which Realtime feature fits?
Supabase Realtime Broadcast lets clients send and receive arbitrary low-latency messages on a named channel, independent of database writes. It suits ephemeral events like cursor positions or chat typing indicators. This differs from features tied to table row changes.
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During a design review, the team wants clients to be notified whenever a row in a table is inserted or updated. Which feature fits?
Postgres Changes streams database row-level insert, update, and delete events to subscribed clients over a Realtime channel. It is built on logical replication under the hood. This is the go-to feature for live-syncing UI state with the database.
3 / 5
In a code review, a dev wants to show which users are currently viewing a document. Which Realtime feature fits?
Presence tracks and synchronizes online/offline state for clients on a channel, such as who is currently active in a shared document. Each client's presence state is broadcast to others automatically. This is purpose-built for collaborative, multiplayer-style UI.
4 / 5
An incident report shows a client received row updates for data it shouldn't see. Which mechanism should be checked?
Realtime respects Row Level Security policies on the underlying table, so leaking updates usually means RLS is missing or too permissive for the subscribing user's role. Enabling and correctly scoping RLS prevents unauthorized rows from being streamed. This is critical for multi-tenant realtime apps.
5 / 5
During a PR review, a teammate groups all realtime interactions for a chat room under one identifier. What is this grouping called?
A Realtime channel is the named topic clients subscribe to, combining Broadcast, Presence, and Postgres Changes scoped to that topic (e.g., a chat room id). All three feature types can share the same channel. This is the organizing unit of Supabase Realtime.