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;

Replication Setup#

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;

Full old Record#

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;

Schema Changes#

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()

Table Changes#

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()

Filter Changes#

Realtime offers filters so you can specify the data your client receives at a more granular level.

eq#

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

// Supabase client setup

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

neq#

To listen to changes when a column's value in a table does not equal a client-specified value:

// Supabase client setup

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

lt#

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

// Supabase client setup

const channel = supabase
  .channel('changes')
  .on(
    'postgres_changes',
    {
      event: 'INSERT',
      schema: 'public',
      table: 'messages',
      filter: 'id=lt.100',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

lte#

To listen to changes when a column's value in a table is less than or equal to a client-specified value:

// Supabase client setup

const channel = supabase
  .channel('changes')
  .on(
    'postgres_changes',
    {
      event: 'UPDATE',
      schema: 'public',
      table: 'profiles',
      filter: 'age=lte.65',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

gt#

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

// Supabase client setup

const channel = supabase
  .channel('changes')
  .on(
    'postgres_changes',
    {
      event: 'INSERT',
      schema: 'public',
      table: 'products',
      filter: 'quantity=gt.10',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

gte#

To listen to changes when a column's value in a table is greater than or equal to a client-specified value:

// Supabase client setup

const channel = supabase
  .channel('changes')
  .on(
    'postgres_changes',
    {
      event: 'INSERT',
      schema: 'public',
      table: 'products',
      filter: 'quantity=gte.10',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

in#

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

// Supabase client setup

const channel = supabase
  .channel('changes')
  .on(
    'postgres_changes',
    {
      event: 'INSERT',
      schema: 'public',
      table: 'colors',
      filter: 'name=in.(red, blue, yellow)',
    },
    (payload) => console.log(payload)
  )
  .subscribe()

Combination Changes#

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()

Custom Tokens#

You may choose to sign your own tokens to customize claims that can be checked in your RLS policies. In order for this to work you must pass apikey in both Realtime's headers and params when creating the client.

The apikey in headers must be either the anon or service_role token that Supabase signed. This will authenticate your request in the API gateway.

The apikey in params can be your custom token signed with the JWT secret of your Supabase project. This is forwarded to the Realtime server and it will verify your custom token and use its claims to authorize database changes when RLS is enabled.

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

const supabase = createClient(process.env.SUPABASE_URL, process.env.SUPABASE_KEY, {
  realtime: {
    headers: {
      apikey: 'supabase-signed-token',
    },
    params: {
      apikey: 'your-custom-token',
    },
  },
})