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CO Delta ExtractionWith delta extraction, only the data that has changed since the last extraction is loaded into theBW. Data that has already been loaded and has not changed is not extracted and does not needto be deleted before a new load. This improves performance compared with periodic extraction ofthe entire dataset.

Determining the Delta Dataset

Delta datasets are determined by the selection of CO line items. This is done using the timestamp (COEP-TIMEST). The time stamp specifies the starting time for determining the deltadataset. SAP R/3 always logs two time stamps at once. These time stamps delimit a selectioninterval for each DataSource (dataset in SAP R/3 or another source system) and each updatemode.

The following update modes are used:

Update Mode Explanation

Delta init Determines the beginning inventory; can be run multiple times foreach DataSource with enhanced selection criteria.

Delta update Determines and loads the delta dataset.

Full update Determines and loads the entire dataset. You need to delete thedata in the BW before reloading.

The time required to update a line item restricts the timeliness of the data in the delta updateanddelta initmodes.

SAP R/3 requires a certain amount of time to update line items. Since the time stamp is set whenthe update begins rather than when it is completed, there may be a lag between the time stampand the actual time of the update event. Because of this lag, some line items may not yet beupdated to the database even though their time stamp is within your selection conditions.Consequently, they cannot be selected when you create a delta dataset and are not loaded intothe BW.

By specifying a safety time (the time during which line items can be safely updated), you canensure that line items are extracted and loaded into the BW despite the lag between the timestamp and the update event. Two hours is the standard value for the safety time.

You should only reduce the standard value for the safety time if you are sure thatyour system can update all line items safely within the new safety time.

You can define the safety time using the BWOM2_V_SAFETYview in the OLTP system asfollows:

You can use different safety times in minutes for each DataSource.

A safety time that does not refer to a DataSource applies to all DataSources for which youhave not made a special entry.

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A database index (index 4) is provided for the COEP CO line item table via the time stamp(COEP-TIMEST). This time stamp is not active in the standard system. In case of performanceproblems, you can improve data extraction performance by activating index 4.

COEP line items cannot be changed after they have been created, except for thedocument text. If the document text is changed in SAP R/3, the COEP-TIMESTMPfield is not updated. For this reason, changed document texts cannot be transferredto the BW using delta extraction.

In full update mode, the system cannot select any CO line items based on the time stamp. Alllineitems that are appropriate for the DataSource and that were selected in the InfoPackage aretransferred to the BW. A subsequent delta update is not possible, as the system does not log atime stamp.

With commitments, the line items are not simply generated once and then never changed (as withthe costs), but are changed on a continuing basis as the commitment is reduced. For this reasonit is not sufficient to extract just the new records to the BW. Instead, all changed records must beextracted and the delta against the previously extracted version of each record must bedetermined. This delta determination takes place in the ODS objects in the BW. In delta mode,therefore, the commitments extractors extract all line items that have changed since the last

delta; these line items are extracted in their changed form (after-image). For this reason,commitments line items can only be analyzed through the use of ODS objects.

Deleted records are a special case. If records are deleted in R/3, they are not extracted. For thisreason, the records are not deleted in the BW. To solve this problem, after the first delta init isexecuted all deleted commitments line items are written to a special R/3 table (COOI_PI), andthis table is extracted as well.

Reducing the Fields in the Transfer Structure

You can define a transfer structure in the BW for each InfoSource and source system. Thetransfer structure contains the fields you selected by means of transfer rules to load thecorresponding data into the BW.

The transfer structure in the BW corresponds to the extract structure in SAP R/3 or anothersource system. The extract structure contains the maximum possible number of fields for which

you can extract data from a source system and load the data into the BW.

To improve performance and minimize the transfer time from the sourcesystem into the BW:

Decide which fields in the extract structure you require for yourreports.

Add only those fields to the transfer structure.

If the standard transfer structures and InfoSources do not meet yourrequirements, copythem and then modify them as needed. All delta-update-

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compatible DataSources are intended as a basis for defining your ownInfoSources.

If you only want to display aggregated data, do notadd the fields documentnumber,posting row, or document row textto your transfer structure.

Loading Actual and Planning Data into the Same InfoCube

You can load actual and planning data into the same InfoCube. You combine data fromInfoSources that are compatible with delta updates, and with InfoSources that are compatiblewith full updates.

SAP provides InfoSources for actual data. These InfoSources contain delta datasets and are thuscompatible for delta updates. Only a full updateis possible for the following data:

Plan values

Down payments

Overall plan values

Variances

Accrual calculations

If you load actual and plan data into the same InfoCube, you need torestrict the value type (0VTYPE) when you create an InfoPackage in theInfoSources that are compatible with full updates. This prevents actual datafrom being loaded from these InfoSources, which would result in the actualdata being duplicated in the InfoCube.

You can load the actual data from the InfoSources that are compatible withthe delta update. This enables you to avoid deleting actual data that alreadyexists in the BW.

If you want to load actual and plan data into different InfoCubes(forexample, actual data into one InfoCube and plan data into another), youneed to restrict the value type (0VTYPE) in the update rules.

InfoSources that are compatible with the delta update have a larger number

of characteristics. For this reason, they provide more detailed information fortheActualvalue type than the InfoSources that are compatible with fullupdates.

The additional characteristics provided by the InfoSources compatible withdelta updates (such as the material number) are notfilled by the system forplanning values in the InfoCube.