Martin Maruskin blog (something about SAP): BW Transformations: HANA runtime

Thursday, December 30, 2021

BW Transformations: HANA runtime

In a BW system that runs on HANA (BW on Hana = BWoH or BW for HANA = BW/4HANA) a transformations can either be running directly in HANA database or in BW application server. In a former case the when the transformations is performed in SAP HANA all data processing happens in the database therefore it is considered as a faster because no data transfer from/to DB to app server is needed. In the latter case, there is an overhead of moving data from DB to app server then data is processed there and finally it need to be moved back to DB - which makes whole processing slower. Now let us have a closer look at processing BW’s transformation in HANA DB that was introduced as of SAP BW 7.4 SP04.

Within the BW transformation a routine called "SAP HANASQLScript" can be created. That is basically HANA SQL script. In BW’s view, the DB script is implemented as a method in AMDP (ABAP managed database procedure) class. Sometimes the script is called as "SAP HANA Expert Script" or "BW-generated Stored Procedure". To create this in SAP GUI (t-code RSTRANGUI) you can use menu Edit -> Routines -> Create SAP HANA Expert Script. This menu path is valid for BW 7.4 based systems. In case of BW 7.5 based systems the menu path was moved to Edit -> Routines -> Expert Routine -> AMDP Script.

To create the same in SAP HANA Studio particularly in "BW Modeling Tools" follow on General tab -> Start/End/Expert Routine Create.

Creating/editing of code of the script takes place in SAP HANA Studio particularly in "ABAP Development tools for SAP NetWeaver (ADT)".

How does the processing of the TRFN in HANA DB it work technically? All business logic that is in TRFN is included in so called "CalculationScenario (CalcScenario)". Meta data of the CalculationScenario are stored in SAP HANA transformation. This object is identified by technical name TR_<ID_for_TRFN> (e.g. TR_00O2SPBEZ1RA5JRZTS4A17Z5O). The TR_* object is also sometimes called as "Analysis Process" or HAP – SAP HANA Analysis Process. It can be seen in t-code RSDHATR. The CalcScenario is embedded into a ColumnView. For data selection from the transformation source when DTP runs it creates SQL SELECT statement based on the ColumnView. Furthermore, during biz logic processing the CalcScenario applies all transformation rules on selected data. While the data is shifted from source to target it is done in single processing step by implementing as an INSERT AS SELECT statement that reads from the ColumnView and inserts into the target database object. While you would observe the HAP in the t-code RSDHATR notice that it is purely a runtime object. That means it can’t be created/modified in the t-code it-self. The CalcScenario can be seen in the t-code as well while switching Expert Mode on/Off in menu Extras. There are an XML representation and Script Definition tabs available.

It is also possible to jump from TRFN definition means t-code RSTRANGUI to HAP. While in the RSTRANGUI select menu Extras -> Display Generated HANA Transformation. This jumps to t-code RSDHATR.