How to Guide - Safety Intervals in Generic Delta

SAP COMMUNITY NETWORK SDN - sdn.sap.com | BPX - bpx.sap.com | BOC - boc.sap.com | UAC - uac.sap.com

2010 SAP AG 1

Safety Intervals in Generic Delta How to Guide

Applies to:

This article talks about safety limits that we can use in Generic Data Source in SAP BI.

For more information, visit the EDW homepage.

Summary

Safety Intervals are used in Generic Data Source to make sure that no data records are missed, even if those are not stored in the DB table when the extraction took place.

Author: Gaurav Namdeo and Debjit Singha

Company: L & T Infotech.

Created on: 13 December 2010

Author Bio

Gaurav Namdeo working in L&T Infotech has an experience 4 years in SAP BI/BO. He has been a part of Development and Implementation Projects.

Debjit Kumar Singha is working in L & T Infotech has an experience of more than 1 year in SAP BI/BO. He has been a part of Development and Implementation Projects.



2010 SAP AG 2

Table of Contents

Step By Step Explanation: .................................................................................................................................. 3

Step 1: ............................................................................................................................................................. 3

Step 2: ............................................................................................................................................................. 3

Step 3: ............................................................................................................................................................. 4

Step 4: ............................................................................................................................................................. 4

Scenario: ............................................................................................................................................................. 5

Example 1: ...................................................................................................................................................... 5

Example 2: ...................................................................................................................................................... 6

Example 3: ...................................................................................................................................................... 6

Example 4: ...................................................................................................................................................... 7

Example 5: ...................................................................................................................................................... 7

Example 6: ...................................................................................................................................................... 8

Related Content .................................................................................................................................................. 9

Disclaimer and Liability Notice .......................................................................................................................... 10



2010 SAP AG 3

Step By Step Explanation: Here we are considering a Z table as the source of data for the data source. The delta specific field is AEDAT Changed On.

Step 1:

Create a Data Source and go to the Generic Delta tab.

Step 2:

Specify the delta specific field (in our case we considered AEDAT) and select Calendar Day.



2010 SAP AG 4

Step 3:

Specify the safety limit.

Step 4:

The delta records can be monitored from RSA7

To find the time stamp click on the respective icon on the Stat tab.



2010 SAP AG 5

Scenario:

Safety Intervals are used in Generic Data Source to make sure that no data records are missed, even if those are not stored in the DB table when the extraction took place. Time stamps got created during extraction and which is in turn used for delta extraction.

Time stamp holds the time (day) of the last data extraction. If in our case, where no safety limits is defined. Suppose Time Stamp holds 11.02.2010 (in mm.dd.yyyy) and the next delta extraction begins on 11.03.2010. In this case after extraction, the pointer is set to 11.03.2010. A document is created on 11:59 PM, 11.02.2010 and not saved until 01:05 AM, 11.03.2010. It is not considered during Initialization (or delta) because it is not saved and it wont be extracted the next time ether (delta).So the safety limit is always picked in such a way that is greater than the maximum time that it takes to create a record (document).

Note: Convention followed

Last Extraction Current day

(Today-3) (Today-2) (Today-1) (Today)

Data loaded from last day extraction Data yet to load as of current extraction.

Data that is going to be loaded again.

Example 1: When Upper and lower limit are blank.

Upper limit = 0 & Lower Limit = 0.

Last Extraction Today Data Loaded in BI (Init)

Yet to load

In case of blank there is always a risk of missing out records. Below image shows the Time Stamp (marker) after delta load.



2010 SAP AG 6

Example 2:

When Upper and lower limit are blank.



Overlap Yet to load

Delta will load data from previous day as well (data will overlap). Below image shows the Time Stamp (marker) after delta load.

Example 3:




Yet to load

For Init as well as Delta both extract one day before data.



2010 SAP AG 7

Example 4:




(Overlap) Yet to load

Example 5:







2010 SAP AG 8

Example 6:





Note: It is always preferred to use upper limit and lower limit together (for system running 24/7), where upper limit describes, how old the data is. Otherwise it is suggested to use upper limit of calendar day. When we are using lower limit, some records may get processed twice, so we have to make sure that those data records are feed in DSO (overwrites the repeated records.



2010 SAP AG 9

Related Content

Delta Load Management Framework Overview

Generic Extraction

Maintaining Generic DataSources

For more information, visit the EDW homepage.



2010 SAP AG 10

Disclaimer and Liability Notice

This document may discuss sample coding or other information that does not include SAP official interfaces and therefore is not supported by SAP. Changes made based on this information are not supported and can be overwritten during an upgrade.

SAP will not be held liable for any damages caused by using or misusing the information, code or methods suggested in this document, and anyone using these methods does so at his/her own risk.

SAP offers no guarantees and assumes no responsibility or liability of any type with respect to the content of this technical article or code sample, including any liability resulting from incompatibility between the content within this document and the materials and services offered by SAP. You agree that you will not hold, or seek to hold, SAP responsible or liable with respect to the content of this document.

Documents

How to Guide - Safety Intervals in Generic Delta