Pre-Step (Archiving Workbench) 

Purpose

The pre-step is an optional process that is separate from the actual data archiving process. It is used to examine the value distribution of the package formation attributes of an archiving object. On the basis of this examination, the pre-step process forms package profiles and stores them in the database.

The parallel archiving subprocesses then use the saved profiles as a basis for package formation.

You can find more information on the pre-step phase, including an explanation of the related terminology (such as package, package limits, package size and package formation attributes), in the Key Terminology section of the SAP Library.

The diagram below shows the role of the pre-step in the data archiving process:

Role of the pre-step in the data archiving process

There are two options for forming packages for parallel data processing with the parallel processing tool:

·       Form packages from the statistical package profiles created beforehand by the pre-step process

We advise you to choose this option if the data to be archived is not distributed evenly.

·       Form packages dynamically at parallel processing runtime without the pre-step process

In this option, the system divides the whole value range of the first package formation attribute used for package formation into a predefined number of intervals of an equal size. These intervals are used to determine the package limits for parallel processing. There are no restrictions on other package formation attributes.

We advise you to choose this option if the data to be archived is distributed evenly.

The diagram below shows the differences between the two options:

Package formation options

The package limits marked in black show the packages defined by the parallel processing tool without a previous pre-step during package formation at runtime. All the intervals are the same size, irrespective of the number of data records they contain.

The red package limits show the packages defined by the pre-step process during a statistical package profile formation. These package limits are adjusted to fit the actual data distribution.

This shows that it is more accurate to form package profiles with the pre-step than to form them dynamically without the pre-step, if the data is distributed unevenly.

The system takes two attributes from the master table (GUID1 and GUID2 here) to form packages. Their data is distributed unevenly. GUID1 could be the key for an account contract, for example, and GUID2 the indicator for the payment items of this account. Even if the key values are distributed evenly when the contract or payment items are created, the distribution may still become uneven if the system posts a large number of payment items to one of the bank’s major customer accounts. Owing to this uneven distribution of the data in the case of the two attributes, the parallel processing of dynamically formed packages may, in extreme cases, be executed more or less sequentially. This is because the runtime of the longest running job determines the overall runtime of the parallel mass run.

Important Notes for Implementing the Pre-Step Process

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      1.      Decide which of the above two options best suits the archiving object in question. You can also give the customers the choice between the two procedures. You make the corresponding setting in the Archiving Workbench step Create Control for Global Archiving Customizing.

      2.      If you want to give your customers the option of forming package profiles with the pre-step process, execute the Generate Pre-Step Program step for the archiving object in question in the Archiving Workbench.

      3.      To enable your customers to execute the pre-step for an archiving object, you must implement at least one specific package profile formation strategy.

      4.      If you develop the strategy function module yourself, you must identify it as the valid package profile formation procedure for the archiving object in the global control of package formation (AFX_GLOBAL_PBP). Make sure this Customizing entry is delivered to your customers as a sample Customizing setting.

      5.      Insert the pre-step into the area menu of your application. Unlike the other archiving subprocesses, the pre-step cannot be started by the Archive Administration.

      6.      Before your customers can start an archiving process based on a statistical package profile, they must execute the pre-step with the relevant profile formation strategy in Productive mode. They then set the archiving mode in the global control in their application implementation guides.

      7.      Before executing the parallel analysis and write processes, your customers must remove the Package Formation at Runtime indicator from their application implementation guides in IMG activity Maintain Global Control of Archiving and enter the relevant package formation procedure.