Data Retrieval 
Purpose
Data retrieval is one of the data warehousing processes in SAP. SAP provides mechanisms for retrieving data (master data, transaction data, metadata) from various sources. You can differentiate as to whether the SAP BW is the target or the source of the data transfer: If data from various sources is retrieved from various sources for transfer into a SAP BW system, the SAP BW system is the target of the data transfer. If the data from SAP BW is retrieved for distribution within the SAP BW or for distribution into analytical applications or other applications, the SAP BW system is the source or hub in relation to data transfer.
The following section will describe
· Which sources are available for data transfer to a SAP BW and how the sources are connected to SAP BW as source systems, along with the ways that the data from the sources can be transferred.
The extraction and transfer of data generally occurs upon request of SAP BW (pull). For more information on how such a data request is established and how the loading process can be monitored in SAP BW under Process Management.
The graphic shows the sources and transfer mechanisms described below:
You can find more detailed information under:
Data Extraction from SAP Source Systems
Transferring Data with UD Connect
Transferring Data with DB Connect
Transferring Data from Flat Files
Transferring Data from External Systems
· Which options there are for Data Transfer within the SAP BW system or in other SAP systems or external applications.
You can find more detailed information under: