A DataReader protocol can include three types of fields, entity codes, entity descriptions and InfoCubes. For each field type the Append/Replace option regulates how and if external data is loaded or discarded. The following paragraph lists the available options for each field type.
[blank]. The incoming record is only loaded if the value found in this field is the code of an existing member of the entity; otherwise the entire record is discarded. This option is used to filter unwanted records.
Append. This option validates all incoming records; when the value from the data source is not the code of an existing member of the entity, a new member is created. This option is used to populate entities.
[blank]. This option only loads the description if the current entity member description field is not populated; therefore only descriptions for newly created items are loaded.
Replace. This option overwrites the entity member description with the value from the source file. It is recommended to always enable this option in order to update entity members descriptions with changes that might occur on the operational system master files.
[blank]. This option adds incoming data to the InfoCube; if the InfoCube already contains values, then the new data is summed. Clearly summing of data occurs only in case where the InfoCube is numeric; for date and text InfoCubes, the current cell value is replaced with the source data.
Replace. This option replaces the InfoCube cells belonging to all time periods found in the incoming data, with the new values. When this option is enabled, the Data Reader performs the following actions
scans the entire source file and memorizes the time periods (i.e. the values of the date field).
then clears the InfoCube cells belonging to the time periods found in the source file.
then starts loading source data into the InfoCube.
For example, consider a file containing transactions for January, February and March 2004. When loading this file, the datareader starts by scanning the date field of all records and memorizes the dates. Then it clears all InfoCube cells for January, February and March 2004 (across all other dimensions) and finally, it reads the values in.