A backfill is a process that streams current rows from a table to a sink.

You can use a backfill to:

  • Seed a sink: Stream the current state of a table to a sink.
  • Replay: Re-process rows that have already been sent to a sink.

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Creating a backfill

During sink creation, you can optionally specify a backfill. Sequin will run the backfill first, then continue to stream any changes to the sink.

After a sink is created, you can manually trigger a backfill on the sink’s backfill tab at any time. You can backfill all tables or specific tables.

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Backfill messages

Sequin will send a message with the action read for each row in the table.

Backfills only include the current state of the row at the time of the backfill. You cannot backfill or replay atomic inserts, updates and deletes to your table.

To enable backfilling of specific inserts, updates and deletes, you can set up change retention.

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Backfill configuration

When creating a backfill, you can indicate whether the backfill should:

  • Stream the whole table.

    Sequin will backfill all rows currently in the table to the sink.

  • Stream starting at a specific point in the table.

    When you add a source table to Sequin, you specify a sort column, like updated_at. You can specify a value for this column to start the backfill at (e.g. updated_at >= '2024-01-01'). Sequin will backfill all rows from the specified point to the end of the table.

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Backfill ordering

Backfills send rows to your sink in the order of the sort column that you specify for your source table. For example, if you specify updated_at as the sort column, Sequin will send rows to your sink ordered by updated_at asc.

Read more about how Sequin backfills work in our blog post.