Limitations

Some limitations apply when you use the CDC Transactions stage to read change data from IBM® InfoSphere® Change Data Capture (InfoSphere CDC) and apply the change data to a target database.

LOB data type truncation

Large object (LOB) data is supported, but there is a maximum LOB size above which the content is truncated. You configure LOB truncation size in the InfoSphere DataStage Properties window of the IBM InfoSphere Change Data Capture Management Console when you configure the subscription.

Define a truncation size for LOB data that ensures that the total length of the output record does not exceed the size of the transport block that can pass between the stages of an IBM InfoSphere DataStage® job. The size of the transport block is specified by the APT_DEFAULT_TRANSPORT_BLOCK_SIZE environment variable. By default, the value of this environment variable is 128 KB. You can increase the size of the transport block. However, increasing this size affects all links and might increase overall memory and disk usage.

For more information about specifying the LOB truncation size, see the InfoSphere CDC documentation.

Transactional integrity

If either of the following statements is true, the overall transactional integrity of the job is not guaranteed:

Reject links are used on the target database connector stage of the job.
The job does not process the data sequentially.

Encryption of sensitive data

Other than connection keys, data transferred between InfoSphere CDC and the CDC Transaction stage is unencrypted. SSL connections are not supported. To provide additional data security, use VPN or SSH tunneling.

Instance recreation

After creating an instance of InfoSphere CDC for InfoSphere DataStage, you cannot delete and recreate the instance without making subscriptions that use the instance unusable. By deleting the instance, you destroy the relationship between and source and target configuration for the subscription. If you destroy this relationship, you must delete the subscription and start again.

DDL awareness

Some versions of InfoSphere CDC do not support DDL awareness. Therefore, if a source table is dropped during replication, no error occurs for some InfoSphere CDC sources. The subscription and corresponding CDC Transaction stage job might continue to run even though the source table no longer exists.