How to create generic delta

How to…
Create Generic Delta

B USINESS I NFORMATION W AREHOUSE

Applicable Releases: SAPI Release 3.0B
August 2002

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HOW TO … CREATE GENERIC DELTA

1 Business Scenario
You want to extract data from Z tables or table that does not have any standard extractors .
This document is written with BW 3.0B and Plug-in 2002.1. It was also tested with BW 2.1C
SP15 & PI 2002.1_46C Support Package 1.

2 The Step By Step Solution
The new generic delta service supports delta extractors on monotonic ‘delta attributes‘ like
Timestamp, Calendar day, Numeric pointer (e.g. document number, counter) – must be
strictly monotonic increasing with time. Only one attribute can be defined as the delta
attribute.

1. Under Transaction SBIW - This
step gives you the option of
creating and maintaining generic
Data Sources for transaction data,
master data attributes or texts from
any kind of transparent tables,
database views or SAP query
functional areas or via a function
module, regardless of application.
This enables you to use the
generic extraction of data.

Please Note: The following example is only used to illustrate how to use the generic delta. For
extracting data from the VBAK table, the Logistics Extraction Cockpit is the recommended method.

©2002 SAP AMERICA , I NC. AND SAP AG 1


2. Create a Generic Data Source
a). Select the Data Source type
and assign a technical name to
it.
b). Choose Create
The screen for creating a
generic Data Source appears.

3. a) Choose an application
Component to which the data
source is to be assigned.
b) Enter the descriptive texts. You
can choose these freely.
c) Choose Generic Delta.



4. Specify the delta-specific field and
the type for this field. Maintain the
settings for the generic delta:
Specify a safety interval.
NOTE: Safety interval should be set so
that no document is missed – even if it
was not stored in the DB table when
the extraction took place. (More Tips at
the end of this document)

4. Select Delta type:
New status for changed records (I.e.
after-image); This can be used with
Data target ODS (AIE).

Additive Delta (I.e. aggregated data
records) (ADD)
Then choose Save.



6. After step 4, the screen of step 3
comes back. Now choose Save again.
This will generate the data source.

After generating the data source, you
will see the Delta Update flag
selected.
In systems as of basis release 4.0B,
you can display the current value for
the delta-relevant field in the delta
queue.

7. Choose Save again.



8. Delta Attributes can be monitored in
delta queue (RSA7). Also note LUW
count does not equal to the changes
records in the source table. Most of the
time it will be ZERO. Delta is enabled
by data selection logic
LUW count can also have value 1.
Whenever delta is extracted, the
extracted data is stored in the delta
queue tables to serve as a fallback, Click
when an error occurs during the
update of the BW system. You will
see a '1' in this field (the extract
counts as one LUW) and are even
able to be displayed in a detail screen.



Example for Determining Selection Intervals with a Generic Delta:
1. For every delta extraction, there is a selection criteria generated: ?last extraction status
(RSA7)” < x <= Today.
2. Offsets for upper and lower delimiter are subtracted from the respective sides
3. Example 1 shows the normal behavior (both offsets = 0), example 2 shows both safety
intervals (offset for lower delimiter = 2, offset for upper delimiter = 1)

4. Offset for lower delimiter can only be defined for delta method “new status for changed
records

Example 1 (both offsets = 0):

already extracted
to be extracted in the next run
last extraction today

Example 2 (offset = 2 resp. offset = 1):

Tips:
1. If delta field is Date (Record Create Date or change date), then use Upper Limit of 1 day.
This will load Delta in BW as of yesterday. Leave Lower limit blank.
2. If delta field is Time Stamp, then use Upper Limit of equal to 1800 Seconds (30 minutes).
This will load Delta in BW as of 30 minutes old. Leave Lower limit blank.
3. If delta field is a Numeric Pointer i.e. generated record # like in GLPCA table, then use
Lower Limit. Use count 10-100. Leave upper limit blank. If value 10 is used then last 10
records will be loaded again. If a record is created when load was running, those records
may get lost. To prevent this situation, lower limit can be used to backup the starting
sequence number. This may result in some records being processed more than once;
therefore, be sure this DataSources is only feeding an ODS Object


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