Delta Migration Guide
This guide aims to give a general understanding of how a Delta Migration works in the context of migration-center
Most migration-center adapters offer the possibility of doing a Delta Migration. For more adapter specific information please consult the documentation for the adapter you are using.
Duplicates, updates and new versions
Migration-center does not scan duplicates
Any document or object scanned in migration-center is considered unique based on its Id_in_source_system value. Therefore scanning the same document multiple times will result in subsequent scan runs ignoring the document to avoid creating duplicates.
Set the loggingLevel parameter to 4 to see each ignored document in the scan run log.
Scanning Updates
If you scan a document and then that document is changed in the source system, scanning the document again will result in an Update Object.
An Update Object has the same Id_in_source_system as the Original Object but the Is_update flag set to true.
Importing Updates
When you import an update object, the importer will get the Id_in_target_system of the Original Object, locate it in the target system and update the content and/or metadata. Therefore you must import the original object before importing the update.
Do not reset or delete any migset containing imported original objects. This will reset its status and delete the Id_in_target_system value, making it impossible for the importer to locate the imported object in the target system. Always use a copy of the migset if you need to use the same configuration.
If the Original Object was not previously imported, you can import both the original and update objects in the same import run.
New Versions
New versions to already scanned documents are not considered update objects and are scanned as new objects linked to the existing ones using the previous_version_object_id attribute.
To import any version, other than the root version of a document, requires its parent version to also be imported. If this was done in a previous run, then do not reset or delete the original migset containing the parent versions. Create a copy of the migset if you need to use the same configuration.
If the parent versions were not imported before you can import all versions together in the same import run.
Delta Migration Process
Initial Migration
An initial migration is done by scanning most or all of the objects from your source system, transforming them and importing to your target system.
Since you can keep the source system active through the initial migration, new documents, new versions and updates can be created after your initial scan was finished.
You can then perform one or multiple delta migrations, which will capture only the new documents and changes.
Delta Scan
You can run the same scanners as during the initial migration or use new ones that go over the same data. These scan runs will contain:
New Objects (have no special requirements and will be imported as usual)
Transformation and Validation
You can use new migsets or copies of the migsets used in the initial migration to transform the objects from the delta scan. This will ensure the migsets from the initial migration are not reset or deleted.
Please see your importer's documentation for any requirements, restrictions and behavior specific to that importer.
Delta Import
During the delta Import you will import the previously scanned new objects, update objects and new versions.
Last updated
Was this helpful?