Terminology

This terminology is important to understand EDB Data Migration Service (DMS) functionality.

Change Data Capture (CDC)

CDC is a set of software design patterns used to determine and track changes in data sets by calculating deltas. EDB Data Migration Service uses CDC to stream changes from a database cluster to another.

EDB DMS Reader

The EDB Data Migration Service Reader, packaged as cdcreader, uses Debezium to perform CDC operations on the source database and Kafka to produce messages containing the change events.

Install and configure the DMS Reader when performing any type of migrations, as it allows you to connect to and read the source. If the target for your migration is an HCP-managed database, you don't need to install the DMS Writer. If the target is another self-managed database, install the DMS Writer.

EDB DMS Writer

The EDB Data Migration Service Writer, packaged as cdcwriter, uses CDC records to replicate and apply changes on the destination database.

Install and configure the DMS Writer on your destination machine when performing migrations to self-managed destination databases, as it allows you to connect to self-managed destinations. Additionally install the DMS Reader for any type of migrations.

Migration types

When creating migrations, you can choose whether to perform a Snapshot or Snapshot + Streaming migration.

Snapshot migration

When you select the Snapshot option, DMS captures an image of your database at a specific moment. This point-in-time copy is then used for the migration. Any new inserts and updates performed on the source database after the snapshot is taken won't be replicated to the destination database.

Snapshot + Streaming migration

When you select the Snapshot + Streaming option, DMS begins with a snapshot to establish a baseline copy, and then constantly employs CDC to apply subsequent changes, ensuring data consistency during migration. DMS continues to stream any data updates performed on the source database to the target database until you mark the migration as completed.

Migration destination types

When creating migrations, you can choose whether to perform a migration to Managed Postgres or to External Postgres.

Managed Postgres

Managed Postgres destinations are databases created and managed through the Hybrid Control Plane. All database clusters created within the project where you are performing the migration can be selected as possible migration destinations.

External Postgres

External Postgres destinations are databases created outside of the Hybrid Control Plane and fully managed by you. To choose an external postgres database as a migration destination, you must first install and configure the DMS Writer to allow the DMS to connect to the self-managed database and perform write operations on it.

Apache Kafka

Apache Kafka is an open-source, distributed-event streaming platform used by thousands of companies for high-performance data pipelines, streaming analytics, data integration, and mission-critical applications. EDB Data Migration Service uses Kafka to manage data streaming from the source to the target database.

Debezium

Debezium is a Java-based, open-source platform for CDC that is supported by the Red Hat community. The EDB DMS Reader uses Debezium to perform reading operations and capture data changes on the source database.