Quick Tip: Preserve Data Consistency in Write-Optimized DSOs

SAP NetWeaver BW preserves the data integrity of delta loads from a traditional DataStore Object (DSO) into all subsequent InfoProviders by default. For example, if a traditional DSO feeds an InfoCube via a delta load, you cannot delete data packages from the source DSO unless you first delete the loaded delta request from the InfoCube. This is designed so that removing the delta from the source still preserves the integrity of the data. Before SAP NetWeaver 7.0 enhancement package 1 (SAP NetWeaver 7.1), no such check existed when loading delta packages from a write-optimized DSO source.

When a delta package is loaded from a write-optimized DSO to a subsequent InfoCube, this integrity can be compromised because, by default, SAP does not provide a delta check when loading from a write-optimized DSO. Therefore, if you load a delta package from a write-optimized DSO to an InfoCube, the system allows you to delete data from the source write-optimized DSO and provides no warning that this could potentially cause problems with the delta feed into the InfoCube.

With a new feature found in SAP NetWeaver 7.1, SAP now provides a check mechanism to prevent data from being deleted from a source write-optimized DSO if this data has been delta loaded to another InfoProvider. The option is called Check Delta Consistency. You can find this option inside the Settings area of the write-optimized DSO screen (Figure 1). Access this screen by going into transaction RSA1, right-clicking the write-optimized DSO, and choosing Change.

Figure 1The Check Delta Consistency option in the write-optimized DSO

When you check this option, the write-optimized DSO acts just like a traditional DSO’s integrity check. If a delta load is successful from the write-optimized DSO to any other InfoProvider, you cannot delete packages out of the write-optimized DSO without first removing the delta package from the subsequent InfoProviders. If you try to delete data from the write-optimized DSO you receive an error (Figures 2and 3). 

Figure 2Delta error message provided when you attempt to delete records from a write-optimized DSO

 

Figure 3Detail from error message when trying to delete write-optimized packages

By default, delta checking is not enabled for write-optimized DSOs, so the selection is unchecked. You must select this option to enable this delta checking. You can select this option even if data exists in the write-optimized DSO. In this case, after selecting this option, you need to reactivate all related transformations.

This feature can help to keep the integrity of delta records because if delta records have been loaded from a write-optimized DSO into a subsequent InfoProvider and then deleted from the source, this could potentially lead to data integrity issues as further data is loaded to the DSO. This might lead to missing or duplicated data which could destroy the integrity of the model. This option can prevent this issue and preserve the integrity of the delta loads.

NoteMore information about SAP NetWeaver 7.1 is at SAP Help via menu path SAP NetWeaver 7.0 EHP1 > Enterprise Data Warehousing (EDW).

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Gary Nolan is an SAP NetWeaver BW-certified independent consultant and author of the SAP PRESS book Efficient SAP NetWeaver BI Implementation and Project Management. He is also a technical editor and frequent contributor to BI Expert. Gary specializes in gathering and evaluating requirements, configuring SAP NetWeaver BW, and providing project management. Gary is a former platinum consultant with SAP America, Inc. He has served as the lead consultant in many projects from the planning, system configuration, and testing phases, through go-live and post-implementation support. You may contact Gary via email at [e-mail].