IBM InfoSphere CDC system parameters allow you to significantly reduce the workload of the target database during mirroring. The IBM InfoSphere CDC apply process groups transactions on the target to reduce the workload. Every commit on the target database will correspond with a commit on the source. However, it may not perform every commit that was done on the source. For example, if the source does three small transactions containing one operation each, the target may commit all three operations as part of a single transaction. You can use this grouping of system parameters to significantly reduce the resources required by the target database. The default settings are appropriate for most databases, but if your target system has limited resources and an increase in latency is acceptable, you can adjust the settings appropriately.
This system parameter specifies the maximum number of transactions that are grouped together before a commit. Normally, commits issued to the target database are in response to commits issued by applications running on the source. You can use this system parameter to manage commits by controlling how often they are issued to the target database. This approach can be used to reduce the overhead of frequent commits to the database.
This system parameter specifies the amount of time, in seconds, before committing small transactions to the target database. Normally, commits issued to the target database are in response to commits issued by applications running on the source. You can use this system parameter to manage commits by controlling how often they are issued to the target database. This approach can be used to reduce the overhead of frequent commits to the database.
This system parameter specifies the number of operations that must be applied to the target database before a commit is issued. Normally, commits issued to the target database are in response to commits issued by applications running on the source. You can use this system parameter to manage commits by controlling how often they are issued to the target database. This approach can be used to reduce the overhead of frequent commits to the database.
This system parameter indicates whether or not the commits that IBM InfoSphere CDC does on the target database will always correspond with a commit that occurred on the source database. If you choose to ignore the commitment control of the source database, IBM InfoSphere CDC allows you to see the partial results of large transactions.
Set this parameter to one of the following:
▪true—Does not ignore the commitment control of the source database. Only records in a committed transaction are mirrored to the target. This setting provides true transaction consistency by ensuring that only committed transactions are sent to the target.
▪false—Ignores the commitment control of the source database. This value disables commitment control for transaction processing. No attempt to maintain transaction consistency is performed during mirroring.
By default, IBM InfoSphere CDC guarantees transactional delivery of change data to the target. This ensures that if any data from a source transaction is committed to the target, then all other in scope operations from that source transaction are committed as well.
In cases where large transactions are done on the source system, it can be more efficient to break a large transaction into smaller transactions when applying data to the target. You can configure this behavior using this system parameter.
The default value of 0 for this system parameter indicates that the product guarantees transactional delivery of change data to the target. A value greater than 0 indicates that you want IBM InfoSphere CDC to break up large transactions into smaller transactions. For example, a value of 2000 indicates that IBM InfoSphere CDC will split up large source transactions so that each transaction committed to the target database contains no more than 2000 operations.
This system parameter identifies the number of rows comprising each transaction during refresh. To reduce the workload on the target database during refresh, IBM InfoSphere CDC periodically commits the changes to the target database rather than performing the refresh as a single large transaction.