Now that there are several “database in the cloud” offerings it is becoming more likely that service subscribers will need some form of real-replication between databases that are on-premise and those that are cloud-based, whether for Disaster Recovery, Data Warehousing, real-time reporting and data integration, or a multi-master site strategy. Since GoldenGate has become Oracle’s strategic technology for replication between traditional on-premise databases it makes sense that they would offer a method that would address “database in the cloud” replication as well.
Choosing the type of public cloud service to implement is important, as GoldenGate software will have to be installed on the server that houses the cloud database. As many cloud providers do not allow direct access to or the installation of software on their Database as a Service (DBaaS) solutions, this means that a Platform as a Service (PaaS) or Infrastrcture as a Service (IaaS) solution is required.
This blog covers replication between a local on-premise Oracle database and an Oracle database in the public cloud. However, the principles discussed apply to other RDBMSs and heterogeneous replication as well.
The approaches that can be used for this scenario are:
1. Using a middle-tier server between the on-premise and the cloud database (no direct communication allowed)
This is a scenario where the cloud and onsite networks are not allowed to directly communicate with each other. Data is pulled by the onsite database using a passive EXTRACT.
The connection can be managed using either of two options:
- The usual PORT and DYNAMICPORT parameters for the GoldenGate MANAGER process.
- SSH SOCKS Proxy tunnels. The onsite system uses port 22 to connect to the mid-tier. Using this method the ACCESSRULE parameter controls which IPs are allowed to connect using this port.
2. Using Passive Extract Pump from cloud to onsite
A direct connection is created here but limited to specific ports. The CAPTURE (EXTRACT) process is standard but a Passive Extract Pump is used to push the data to the target. This Pump process is controlled by the on-premise side. This option is also able to use SSH SOCKS.
Gallery: Architecture overview diagrams for both options:
Please contact Cintra if you would like further information on the capabilities of Oracle GoldenGate or to assist with the design and configuration of a real-time replication solution.
Written by Michael Paddock, Principal DBA, Cintra Texas – October 2015