Hi Everybody!
I want to have a discussion with you about the approach for implementing a SAP Hana model with Multi-Temperature Data Management HOT+COLD data. The approach to manage WARM data is “easily” implemented through Dynamic Tiering using SAP Hana server to hold historical data into its own disk space so you don’t have to worry too much about data replication and handling the change of data temperature (use this for reference http://help.sap.com/saphelp_nw74/helpdata/en/f6/99e81daef24dfa8414b4e104fd76b7/content.htm).
Instead, we have some trouble understanding what happens when we implement an HOT+COLD with Near Line Storage: data are not resident in SAP Hana anymore and when we think about some questions, we cannot find any guideline or recommended approach for specific topics like the followings:
1. What about data replication?
This academy illustrates the approach for moving data in extended tables (applicable for Near Line Storage through SDA also) https://www.youtube.com/watch?v=ae1qIViv5sk but what happens when data replication from SAP ERP (SLT) is involved? It is simple to manage new insertions with a stored procedure in SAP Hana and moving cold data to external storage, but how can we manage deletions? And what a about updates? Those are triggered in the HOT table and so I think we will lose them.
2. Data consistency
How do you move data into COLD tables? In our team, we decided to maintain data consistency through header-items tables: If we move a header’s record into the external storage we also move the item’s record.
This approach has some advantages (we can query HOT data and be sure that both header and items are in hot storage) and disadvantages (we have to implement a custom migration logic for each group of tables).
What you find is the best approach for this purpose?
I am looking forward to hear you opinion!
Manuel