This guide shows you how to set up Postgres change data capture (CDC) and stream changes to an S2 stream using Sequin.

With Postgres data streaming to S2 you can trigger event-driven workflows, feed analytics pipelines, and fan-out events to other services.

By the end of this how-to, you’ll have database changes flowing to an S2 stream.

This is the how-to guide for streaming Postgres to S2. See the quickstart for a step-by-step walkthrough or the reference for details on all configuration options.

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Prerequisites

If you’re self-hosting Sequin, you’ll need:

  1. Sequin installed
  2. A database connected

If you’re using Sequin Cloud, you’ll need:

  1. A Sequin Cloud account
  2. A database connected

And for S2 you’ll need:

  1. A S2 Cloud account
  2. The S2 CLI installed (optional but recommended)

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Basic setup

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Create an S2 Access Token

In the S2 web console, open the Access Tokens page and click + Issue to generate a new token.

Save this token in a secure location—you’ll use it to configure both the S2 CLI and your Sequin S2 sink.

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Create a basin and stream

If you don’t already have a basin and stream, create them via the S2 console or the CLI:

# Configure the CLI with your access token
s2 config set --access-token <your-access-token>

# Create a basin
s2 create-basin my-basin

# Create a stream called `products` inside that basin
s2 create-stream s2://my-basin/products

You can also perform these steps in the S2 console by navigating to Basins → + Create Basin and then + Create Stream.

You can configure S2 Basins to automatically create streams when you create a new sink in Sequin by enabling the Create stream on append option in the S2 console or passing the --create-stream-on-append flag to the s2 create-basin command.

Your S2 stream is now ready to receive data.

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Create an S2 sink

Navigate to the Sinks tab in the Sequin console, click Create Sink, and choose S2 as the sink type.

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Configure the source

1

Select source schemas and tables

Under Source, pick the schemas and tables you want to stream data from.

2

Specify filters

You can restrict to insert, update, and/or delete actions, and you can apply additional filters.

3

Specify backfill

Optionally send a backfill of existing rows. Disable Backfill if you only want new changes.

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Configure S2

1

Enter connection details

In the S2 configuration card, enter:

  • Basin – the basin name you created earlier (e.g. my-basin)
  • Stream – the stream name (e.g. products)
  • Access Token – the S2 access token you generated
2

Create the sink

Give your sink a name and click Create Sink.

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Verify & debug

To verify that your S2 sink is working:

  1. Make a change in your source table.

  2. Confirm that the Messages count for your sink increases in the Sequin console, and observe the new message in the Messages tab.

  3. Use the S2 CLI to read from the stream and confirm events arrive:

    s2 tail -f s2://my-basin/products

If messages don’t seem to be flowing:

  1. Open the sink’s Messages tab to inspect in-flight, failed, and delivered messages.
  2. Click a failed message to see delivery logs and error details returned by S2.

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Next steps

  • Process the events

    Build a consumer that reads from your S2 stream and processes the data.

  • Deploy your implementation

    When you’re ready, follow “How to deploy to production”.

  • Advanced configuration

    Learn about batching, ordering guarantees, and other options in the S2 sink reference.

  • Start from scratch

    If you need a more guided tutorial, check out the S2 sink quickstart.