Showing posts with label sap-bw. Show all posts
Showing posts with label sap-bw. Show all posts

Saturday, 1 April 2017

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.

Wednesday, 4 January 2017

Constant Selection in SAP HANA Using Dynamic Join

In SAP BW, there is this concept of “Constant Selection” where you can mark a selection in the Query Designer as constant. This means that navigation and filtering will have no effect on the selection at runtime.

In SAP HANA, there is no feature that directly supports this functionality. We have to model it ourselves. One way to implement it is through “self joins” and “dynamic joins”.