This topic describes the limitations, applicable scenarios, and procedure for setting the incremental synchronization start timestamp when you create a data migration or synchronization task.
Limitations
When you create a data migration or synchronization task, if you set the Incremental Synchronization option for Migration/Synchronization Type and did not select Full Migration/Full Synchronization, the system supports setting the incremental synchronization start timestamp.
When you set the incremental synchronization start timestamp, you can select the current time or a point in time before the current time, which must be earlier than the expiration or archiving time of incremental logs in the source database.
Applicable scenarios
You can set the incremental synchronization start timestamp to achieve the following scenarios:
Before you create a data migration or synchronization task, you ensure that the data in the source and target databases is consistent. You want to obtain incremental data after a specific point in time and synchronize the incremental data to the target database.
You do not need historical data in the source database and want to synchronize incremental data after a specific point in time to the target database.
Procedure
Configure the data migration or synchronization task to the Select Migration Type or Select Synchronization Type step.
For more information, see Data migration or Data synchronization according to your task type.
On the Select Migration Type or Select Synchronization Type page, select the required type as needed. Make sure that you select the Incremental Synchronization option and do not select Full Migration/Full Synchronization.
Continue to complete the configuration to the Migration Options/Synchronization Options page. In the Incremental Synchronization Start Timestamp section, specify the time when you want to start synchronizing data. By default, the current system time is used.
Note
Based on the migration/synchronization type that you selected, the page displays different parameter settings. This section describes the incremental synchronization start timestamp in detail. For more information about other parameters, see the documentation of the data migration module.
You can select a specific point in time or enter the timestamp. The specified point in time is closely related to the retention period of incremental logs in the source database. If no special requirements exist, you can set the current point in time as the start timestamp.
If you have selected Obtain Incremental Data through Kafka for an Oracle data source, configure the timestamp when the incremental data that is delivered to Kafka by OGG is written to the Kafka message. The incremental synchronization reads incremental data after the specified timestamp.
Click Precheck. If the precheck is successful, start the task.