When you update a product description, you want to update your search index.

Replicate changes with Sequin
  1. Sequin captures every row on your products table using a durable replication slot.
  2. It then delivers the changes to your search index.
  3. With a simple HTTP interface, replays, and observability built in you can ensure the search index is always up to date.

This is a common replication pattern. This guide shows you how to implement replication with Sequin.

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Implementation

Connect your database to Sequin

  1. Login to your Sequin account and click the Connect Database button on the dashboard.
  2. Paste the connection string for your database (or enter your connection credentials).
  3. Create a replication slot and publication for Sequin using the SQL commands in the console.
  4. Name your database and click Connect Database to finish.

Your database is now connected to Sequin. If you’d like a step-by-step guide, check out our Quickstart.

Create a consumer to capture row changes

Create a consumers that captures every row in your products table:

  1. Click the Create Consumer button and then select the users table.
  2. Because you want to capture every row change you can leave the Filter field blank.
  3. Select the Rows option and then choose Push for the consumer type.

By configuring the consumer to capture Rows Sequin will send a message for every row change in the table. You can also replay and backfill the entire table to ensure your search index is up to date.

  1. Enter the the HTTP endpoint where Sequin will send the changes. Add any headers you need to authenticate the request.
  2. Click Create Consumer to finish.

Your consumer is now created. If you’d like a step-by-step guide, check out our Quickstart.

Invalidate and update your search index

Every time a row in your products table is updated Sequin will send a message to your webhook endpoint:

{
  "record": {
    "id": 1,
    "name": "NVIDIA H-100 GPU",
    "description": "High-performance AI and HPC accelerator",
    "price": 30000.00,
    "in_stock": true,
    "compute_capability": "9.0",
    "memory_size_gb": 80
  },
  "metadata": {
    "table_schema": "public",
    "table_name": "house_atreides_members",
    "consumer": {
      "id": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
      "name": "dune_characters_consumer"
    }
  }
}

You can handle this message in your application and update your search index:

// Webhook handler for updating search index
app.post('/webhook/update-search-index', async (req, res) => {
  const { record } = req.body;

  try {
    // Assuming you're using a hypothetical searchIndex object
    await searchIndex.upsert({
      id: record.id,
      name: record.name,
      description: record.description,
      price: record.price,
      in_stock: record.in_stock,
      compute_capability: record.compute_capability,
      memory_size_gb: record.memory_size_gb
    });

    res.status(200).send('Search index updated successfully');
  } catch (error) {
    console.error('Error updating search index:', error);
    res.status(500).send('Error updating search index');
  }
});

Importantly, to ensure that every product update is reflected in your search index, Sequin will retry the message until the HTTP request is acknowledged with a 200 status.

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Benefits

Sequin captures every change in your products table via the WAL and then ensure that each change is processed to update your search index. Sequin handles the hard parts for you:

  • Transactional guarantees: Sequin ensures that every new order is processed by each service.
  • Reliable retries: Sequin will retry failed HTTP requests until they are acknowledged.
  • No custom infrastructure: You don’t need to run any custom infrastructure to send emails.
  • Backfill: Sequin can replay the entire table to ensure your search index is up to date.
  • Replays: Sequin can replay data from a specific point in time.
  • Observability: Sequin provides observability into the replication process and the HTTP requests being sent.

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Next steps

To add a fan out pattern to your application, you might want to:

  • Go through our Quickstart guide to connect your database to Sequin and create a consumer.
  • Learn more about how Sequin works under the hood in the Core Concepts section.

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