Скачать или смотреть SAP BW-Generic Delta Calday Delta Part 1

Generic Delta Calday Delta" is a technique for extracting data incrementally in SAP BW by using a date field, where "Generic Delta" is a method for incremental data loading and "Calday" is the delta type that uses a calendar day field. It is used to extract records from the previous day by setting an upper limit of '1' on the delta and leaving the lower limit blank for a date/time field. A safety interval can be set to ensure all records are captured, even if postings occur during the extraction.
How it works
Generic Delta: A method for extracting data from non-SAP or custom sources where a standard delta mechanism isn't available. It uses a specific field to track changes.
Calday Delta Type: The delta is based on a calendar day field (e.g., AEDAT in SAP).
Delta Calculation:
The system stores a "last run date" and the next extraction begins from that date.
It extracts records from the last run date until the current date.
Safety Interval:
Upper Limit: This is a number of days added to the current date to avoid missing records if the extraction takes a while. A common setting is 1 day. For example, if today is January 20, setting an upper limit of 1 will extract records from yesterday (January 19) up to today, and the delta pointer will be set to the end of today's date for the next run.
Lower Limit: This can be set to extract records that may have been posted on the same day after the last extraction. Setting a lower limit of 100 for a numeric pointer type, for instance, means records will be extracted again, even if they were already extracted.
When to use it
Use the CALDAY delta when your data source has a date field and you want to extract data on a daily basis.
Use the upper limit for safety to avoid missing records, especially if the extraction takes some time.
Use the lower limit to ensure all records are captured, but be aware that this may lead to duplicate records in some cases.
Example
If you set an upper limit of 1 for the calendar day and run the delta on January 20, the extraction will retrieve all records from January 19 up to the current date of January 20.
After the extraction, the delta pointer will be updated to January 20, so the next delta run will start from that date.