Скачать или смотреть SAP BW-Generic Delta Calday Delta Part 2

"Generic Delta" refers to an extraction method in SAP BW/BI for pulling incremental data from a custom data source. A "Calday" or "Calendar Day" delta is a specific type of generic delta that uses a date field (like AEDAT) to extract data based on the previous day's records. A "Part" or "delta pointer" is the mechanism within this process that tracks which data has been extracted and is used to determine what new data to pull in subsequent extractions.
Generic Delta with Calday
Purpose: To extract data incrementally based on a date field.
Field Type: Requires a generic data source with a date field (e.g., AEDAT), typically in yyyy.mm.dd format.
Extraction Logic:
Delta Pointer: The system tracks the date of the last extraction to know what to pull next.
Safety Interval: A safety upper limit is set to ensure records aren't missed if they are posted to the source system during an extraction. A common setting is 1 day.
Example: If a delta extraction is run on January 20th, the system will pull all records with a creation date up to January 19th. The delta pointer is then updated to January 19th for the next run.
Delta Pointer
Purpose: To track the last extraction point and ensure all new records are pulled in the subsequent delta extraction.
How it works:
It can be a date field (for CALDAY) or a sequential number (for Numeric Pointer).
It is a mechanism that keeps track of the last time a data source was successfully extracted.
When a new delta extraction is triggered, the system uses the delta pointer to extract all records with a date/value after the last recorded point.
Other Delta Types: While CALDAY is based on a date, other types of generic delta extraction include:
Timestamp Delta: For sources with a timestamp field (e.g., yyyy.mm.dd.hh.mm.ss), it's common to use a timestamp field to extract data based on a specific time interval.
Numeric Pointer Delta: For sources without a date or timestamp field, a unique, monotonically increasing field (like a document number) can be used.