BI7 : Change full load to delta load - things to do?

Question

http://wiki.sdn.sap.com/wiki/display/profile/2007/04/30/Differencebetweenfull,intialanddeltaupdatemodes
Difference: Full load, Delta Load & INIT load in BW
Hi.
Since am not familiar with BW request clarity as to how to achieve the following :
We are on BI 7.
On our BW server, One of the Existing process chain loads data as full load daily Till date.
This schedule runs for about 4 to 6 hours during the nights. And the data seems to be growing.
And doing full load, now seems, not that meaningful for data analysis.
So we now feel we need not do a full load every day. But do only the incremental load.
How to make this effective in our existing process chains.
I went thro the 2 links above, but a few things am not clear.
What exactly needs to be done to change a full load into a delta load.
Also do not wish to have any data loss happening.
We run the schedules on a particular process chain for BW around 1 am.
Say from tomorrow I want to have the data loading as delta.
What exactly are the steps to be followed.
Precautions to be taken
So that we have the correct data load and no data is lost - while doing this.
Things to do am not clear :
do initialization with data transfer / or without data tranfer ?
The make it delta?
So that from tomorrow all data loading becomes delta ?
Or
since in our scenario,
daily basis it is full load.
Just make it delta load,
so that whatever changes will run in the next days schedule.
What all things are to be done stepwise.
if anyone could advise.
That would be very helpful.
Also any documentation which explains all these if someone could share the link please ?
Many thanks
indu
Edited by: Indumathy Narayanan on Aug 26, 2011 5:50 PM

Answer 1

Hi,
Kindly look at following links as well
http://help.sap.com/saphelp_nw04s/helpdata/en/44/9821620553053de10000000a1553f6/content.htm
Generic Delta
If a field exists in the extract structure of a DataSource that contains values which increase monotonously over time, you can define delta capability for this DataSource. If such a delta-relevant field exists in the extract structure, such as a timestamp, the system determines the data volume transferred in the delta method by comparing the maximum value transferred with the last load with the amount of data that has since entered the system.  Only the data that has newly arrived is transferred.
To get the delta, generic delta management translates the update mode into a selection criterion. The selection of the request is enhanced with an interval for the delta-relevant field. The lower limit of the interval is known from the previous extraction. The upper limit is taken from the current value, such as the timestamp or the time of extraction. You can use security intervals to ensure that all data is taken into consideration in the extractions. After the data request was transferred to the extractor, and the data was extracted, the extractor then informs generic delta management that the pointer can be set to the upper limit of the previously returned interval.
The delta for generic DataSources cannot be used with a BW system release prior to 3.0. In older SAP BW releases, the system does not replicate DataSources for master data and texts that were made delta-enabled using the delta for generic DataSources.
Determining the Generic Delta for a DataSource
       1.      Choose Generic Delta.
       2.      In the subsequent dialog box, specify the delta-determining field and the type for this field.
       3.      Maintain the settings for the generic delta:
                            a.      Specify a security interval.
The purpose of a security interval is to make the system take into consideration records that appear during the extraction process but which remain unextracted (since they have yet to be saved) during the next extraction.
You have the option of adding a security interval to the upper limit/lower limit of the interval.
A security interval should only be specified for the lower limit when the delta method results in a new status for changed records, in other words, when the status is overwritten in BW. In this case, duplicate data records that could arise in such a safety interval have no affect on BW.
                            b.      Choose the delta type for the data to be extracted.
The delta type is used to determine how extracted data is interpreted in BW and which data targets in which it can be posted.
With the delta type additive delta, the record to be loaded for summarizable key figures only returns the change to the key figure. The extracted data is added in BW. DataSources with this delta type can supply both ODS objects and InfoCubes with data.
With the delta type New Status for Changed Records, every record to be loaded returns the new status for all key figures and characteristics. The values are overwritten in BW. DataSources with this delta type can write the data into ODS objects and master data tables.
       4.      Save your entries.
Delta transfer is now possible for this DataSource.
After generating the DataSource, you can see this from the marking for the field Delta Update on the DataSource: Customer Version screen.
In systems from release 4.0B, you can display the current value of the delta-relevant field in the delta queue.
Thanks and regards