Home

Postgres Changes

Realtime's Postgres Changes feature listens for database changes and sends them to clients. Clients are required to subscribe with a JWT dictating which changes they are allowed to receive based on the database's Row Level Security.

Anyone with access to a valid JWT signed with the project's JWT secret is able to listen to your database's changes, unless tables have Row Level Security enabled and policies in place.

Clients can choose to receive INSERT, UPDATE, DELETE, or * (all) changes for all changes in a schema, a table in a schema, or a column's value in a table. Your clients should only listen to tables in the public schema and you must first enable the tables you want your clients to listen to.

Postgres Changes works out of the box for tables in the public schema. You can listen to tables in your private schemas by granting table SELECT permissions to the database role found in your access token. You can run a query similar to the following:

GRANT SELECT ON "private_schema"."table" TO authenticated;

caution

We strongly encourage you to enable RLS and create policies for tables in private schemas. Otherwise, any role you grant access to will have unfettered read access to the table.

You can do this in the Replication section in the Dashboard or with the SQL editor:

begin;
  -- remove the supabase_realtime publication
  drop publication if exists supabase_realtime;

  -- re-create the supabase_realtime publication with no tables
  create publication supabase_realtime;
commit;

-- add a table to the publication
alter publication supabase_realtime add table messages;

By default, only new record changes are sent but if you want to receive the old record (previous values) whenever you UPDATE or DELETE a record, you can set the replica identity of your table to full:

alter table messages replica identity full;

To listen to all changes in the public schema:

const { createClient } = require('@supabase/supabase-js')

const supabase = createClient(process.env.SUPABASE_URL, process.env.SUPABASE_KEY)

/*
  Channel name can be any string.
  Event name can can be one of:
    - INSERT
    - UPDATE
    - DELETE
    - *
*/
const channel = supabase
  .channel('schema-db-changes')
  .on(
    'postgres_changes',
    {
      event: '*',
      schema: 'public',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

To listen to changes on a table in the public schema:

// Supabase client setup

const channel = supabase
  .channel('table-db-changes')
  .on(
    'postgres_changes',
    {
      event: 'INSERT',
      schema: 'public',
      table: 'messages',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

To listen to changes when a column's value in a table matches a client-specified value:

// Supabase client setup

const channel = supabase
  .channel('value-db-changes')
  .on(
    'postgres_changes',
    {
      event: 'UPDATE',
      schema: 'public',
      table: 'messages',
      filter: 'body=eq.hey',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

To listen to different events and schema/tables/filters combinations with the same channel:

// Supabase client setup

const channel = supabase
  .channel('db-changes')
  .on(
    'postgres_changes',
    {
      event: '*',
      schema: 'public',
      table: 'messages',
      filter: 'body=eq.bye',
    },
    (payload) => console.log(payload)
  )
  .on('postgres_changes',
    {
      event: 'INSERT',
      schema: 'public',
      table: 'users',
    },
    (payload) => console.log(payload)
  )
  .subscribe()
Need some help?

Not to worry, our specialist engineers are here to help. Submit a support ticket through the Dashboard.