HANA – table unload priorities

Many people still think all data in HANA which exists in the data area also loaded into memory all the time. Of course there are some techniques which influence the unload / placement of tables e.g. data aging and the non-active data concept of BW. Usually unloads happen based on a “least recently used” (LRU) approach, so the columns having not being used for the longest time are unloaded first. So HANA decides when it makes sense to unload some tables to free memory.

But what about your own tables? Can you also take influence when data are unoaded? For general information you can refer to 2127458 – FAQ: SAP HANA Loads and Unloads. Ok you can manually unload or load tables. But you want to do this automatically and want to understand when tables are loaded or unloaded.

SAP BW Extractor ( DataSource) based on HANA Model

In this blog, I would discuss how can we load data from HANA models/Database Procedure  to BW DataSource based on Function Module.

Scenario 1 : 
You have a HANA model which gives you  every day snapshot of open order / delivered order in real time . You want to store the data somewhere  to see trend over time.  Reporting security is implemented in BW side and you want to reuse that .You also want to use Master Data / Text available in BW.

Scenario 2: 
You have BW on HANA and HANA native in same database , and there is hybrid data model which uses data from both BW Schema and HANA native schema.  If the tables are small , you might pull the data by  some way and build your model in BW . However, if the tables are big and requirement is not straight forward, a calculation view can be handy and comes with great performance benefit by using Input Parameter.  We can also model very complex requirement by using  stored  procedure or Script Based Calcuation view.  But , for some reasons we want data to be persisted in BW , like business wants Key and Text side by side for variable help values which still does not work well in native HANA.