(GLUE-1812) BW Delta Mechanisms

Delta mechanisms (deltas) specify how data is extracted. Currently, the BW delta functionality is supported only for the extraction from a SAP BW system to a storage.

Deltas serve only as data source definition and do not specify higher purpose processes like replication, offloading, etc. Based on the type of the extractor Glue executes the following BW delta types:

Change log delta

This delta reads data based on Change log table of an InfoProvider. The initial full load reads data from the Active table of an InfoProvider. Then the delta is automatically initialized with activation request values currently available in the Change log table. Next load reads data from the Change log table, reading only records with activation request values that weren't loaded yet, so only records with new request values are transferred during the next execution of an extractor.

Delta properties

Properties contains general information about the extractor and the delta details:

• Delta type
• Status - actual status of the extractor (Saved or Active)
• Source - the name of a source InfoProvider
• Last extraction - date and time of the last extraction
• Full load - indicates whether a full load was executed

The Properties section shows

• Truncate target table - if you select this checkbox, then before a new extraction all data in the target table is deleted.

Set up values which will be exported from the Change log

Select at least one Record mode value which should be exported from the Change log table of the DSO. The Record modes is a SAP functionality, you can find more information in the section "0RECORDMODE Values" of the blog Recordmode and delta type concepts.

_{Delta Tools - Properties tab}

Manage

In Manage you may execute data extractions.
Perform delta run executes a standard delta extraction.
Perform full load executes a full load even if it was already performed. By the first full load the Change log delta is initialized. If you execute the full load repeatedly, the delta values aren't updated.

_{Delta Tools - Manage tab}

Request delta

Request delta reads data based on DTP requests loaded into an InfoProvider. During the initial full load, all data is read from an InfoProvider and the delta is initialized with the highest request value. Then, the next load reads data with DTP request values greater than current maximum. The maximum DTP request value is then updated to a new value.

Delta properties

Properties tab contains general information about the extractor and the delta details:

• Delta type
• Status - actual status of the extractor (Saved or Active)
• Source - the name of an InfoProvider
  
• Last extraction - date and time of the last extraction
• Full load - indicates whether the full load was executed

The Properties section shows

• Highest loaded value - Greatest loaded value of an InfoProvider DTP request.

Manage

Manage functionality isn't currently supported for request-based delta extraction.