Number of CDC Subscriptions Required
A Subscription is a logical container that describes the replication configuration for tables from a source to a target datastore. Once the subscription is created, you create table mappings within the subscription for the group of tables you wish to replicate
An important part of planning an InfoSphere CDC implementation is to choose the appropriate number of subscriptions to meet your requirements
More information can be found in the CDC performance documents :
For a comprehensive list of best practices, please see the parent community main page:
Rule of Thumb:
- Starting with the minimum number of subscriptions and only increasing due to valid reasons, is the optimal approach
- This will ensure efficient use of resources as well as require a lower level of maintenance
It may require an iterative process before you have a good balance
- The number of subscriptions will impact the resource utilization of the server (more CPU and RAM are needed) and performance of InfoSphere CDC
- Note that tables with referential integrity or ones where the data must be synchronized at all times must reside in the same subscription since different subscriptions may be at different points in the log
- The following are valid reasons to increase the number of subscriptions:
- Requirement to replicate one source table to multiple targets
- You need to increase the number of applies once it has been determined that it is the apply that is affecting the performance and you want further parallelism
- Management of replication for groups of tables, in cases where some tables only require mirroring with a scheduled end time, while others require continuous or they are active at different times of the day
- You have too many tables in a single subscription which is affecting start-up performance
- You have multiple independent business applications that you need to mirror, but want to be able to deal with maintenance independently
