title: 'Changes Refresh Mode' sidebar_label: 'Changes' description: 'Apply incremental inserts, updates, and deletes via Change Data Capture.' sidebar_position: 3 pagination_prev: null pagination_next: null

The changes refresh mode applies incremental inserts, updates, and deletes from a Change Data Capture (CDC) (opens in a new tab) source. Unlike append, changes mode reflects modifications and deletions in the acceleration, keeping it consistent with sources where rows mutate over time.

Use changes when:

• The source supports CDC (e.g., a database with a transaction log).
• Rows in the source are updated or deleted, not just inserted.
• The acceleration must reflect the current state of the source row-for-row.

Configuration

refresh_mode: changes requires a CDC-capable data connector. Spice supports CDC via PostgreSQL Logical Replication (opens in a new tab), MongoDB Change Streams (opens in a new tab), DynamoDB Streams (opens in a new tab), and Debezium (opens in a new tab) (over Kafka). See Supported Data Connectors (opens in a new tab) for details.

:::note

Apache Kafka (opens in a new tab) is a real-time streaming source but is append-only — it uses refresh_mode: append (opens in a new tab), not changes.

:::

datasets:
  - from: debezium:cdc.public.customer_orders
    name: customer_orders
    acceleration:
      enabled: true
      refresh_mode: changes
      engine: duckdb
      mode: file

datasets:
  - from: debezium:cdc.public.customer_orders
    name: customer_orders
    acceleration:
      enabled: true
      refresh_mode: changes
      engine: duckdb
      mode: file

The Debezium connector streams change events from a Kafka topic produced by Debezium. Each event is applied to the acceleration in order, preserving inserts, updates, and deletes from the source.

Behavior

• The acceleration is bootstrapped from the source snapshot, then continuously updated from the change stream.
• refresh_check_interval, refresh_cron, on-demand refresh, refresh_data_window, and retention_period do not apply — updates are driven by the change stream rather than periodic polling.
• refresh_sql (opens in a new tab) can only modify selected columns in changes mode and cannot apply row filters.

Related Topics

• Change Data Capture (opens in a new tab)
• Debezium Data Connector (opens in a new tab)