Non-functional requirements (NFRs)
Irrespective of the functional requirements, the design must also include the non-functional requirements (NFR) in order to achieve the overall goal of delivering a robust, high performance, and stable system.
Latency
One of the main NFRs is performance. How long does it take to replicate a transaction from the source database to the target? This is known as end-to-end latency that typically has a threshold that must not be breeched in order to satisfy the specified NFR.
GoldenGate refers to latency as lag, which can be measured at different intervals in the replication process. These are:
Source to Extract: The time taken for a record to be processed by the Extract compared to the commit timestamp on the database
Replicat to Target: The time taken for the last record to be processed by the Replicat compared to the record creation time in the trail file
A well designed system may encounter spikes in latency but it should never be continuous or growing. Trying...
