Data Replication Models
Oracle GoldenGate can be installed on the local server as the data source or target, or on a remote server as source or target. Oracle GoldenGate processes can connect to the database by configuring a network connection from Oracle GoldenGate to the database. For example, in Oracle or non-Oracle database server, the connection from the Extract, Replicat, and Microservices are made using Database Network, and can run on a separate server from the database server.
This section covers different aspects of setting up a local deployment when installing Oracle GoldenGate or remote deployment, when installing Oracle GoldenGate on a hub.
Replication Using Local Deployment
When replicating using a local deployment, the Oracle GoldenGate instance runs on the database server using a local connection to the database, as shown in the following diagram.
Description of the illustration multi_hub_ff.png
In this diagram, two Oracle GoldenGate deployments are set up on two different database servers, which are connected over the network. Consider, Data Center 1 as the source and Data Center 2 as the target. Both the deployment are local to their respective database server. However, the databases reside in different regions or servers and use a Distribution Service / Receiver Service pair to send the trail files across the network.
The following diagram displays the workflow of an Oracle GoldenGate deployment in a database server within a local hub.
Description of the illustration gg_single_hub.png
This diagram is described using the following points:
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1: Capture of committed transactions that can be filtered as they occur by reading the transaction keys)
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2: Trail is sent using canonical, secure and wire protocol for data transaction and events.
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3: Distribution/Receiver Services send and receive data across the service mesh.
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4: Route transactions are compressed, encrypted for routing to targets
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5: Delivery applies data with transaction integrity
Replication Using a Hub
When replicating using a hub configuration, the Oracle GoldenGate instance runs on an individual Server, Instance (like a compute instance), or Host and connects remotely to the database. This case is used mostly when you want to limit the overhead of Oracle GoldenGate on the source or target databases, or the database environment does not allow the software to be installed locally on the database server.
Most remote Extracts, except for SQL Server, can tolerate up to 80ms round trip ping time between the source database and the server where the Extract process is running. This provides a lot of flexibility in deciding where the server running the Extract process can be physically located. This feature enables capturing remotely in mutiple scenarios, especially for cloud databases. For example, it allows capturing remotely where the Extract process is running on a compute node in the same region, or in an on-premises data center, or in another region or cloud provider providing the network ingress and the egress is configured to allow for the client connection.
For best performance, Oracle recommends running the Extract process as close to the source database as possible.
Remote Replicats are highly dependent on low network latency because each network operation requires an acknowledgement before the next can be issued. Oracle recommends that the round-trip ping time between the server running the Replicat process and the target database be as low as possible, and typically any values higher than 4 ms will increase the Replicat lag.
In hub models, both the Extract and the Replicat for the same replication stream are deployed on the same server, so, there is no need for a Distribution Path. The Extract writes to a local trail file, and the Replicat reads from that same trail file. However, in some topologies, a hub might be deployed close to the source database, with an additional hub located near the target database. In these cases, changes are routed through the Distribution Path from the source hub to the target hub.
In the following diagram of a hub deployment, the Extract and Replicat processes operate from the same Oracle GoldenGate server and connect remotely to the source database.
Description of the illustration gg_hub.png
This configuration can have multiple Oracle GoldenGate installations with multiple deployments managing a fleet of replication streams with similar or different topologies and use cases.
Replication Using a Hybrid Model
Replication in a hybrid deployments with Oracle GoldenGate can be done by mixing local and hub deployments together and connect different deployments through Distribution Paths.
In the following hybrid deployment, Oracle GoldenGate software is installed locally on the source database and connects remotely to the target.
