So we discussed the basic Architecture in the last part. Today I will explain the scenarios in which HANA Database can be used.
Before that I would just brief you about the concept of Row Store and Column Store:
Row Store is the usual way of storing data in relational databases such as DB2. Row store is Write-Optimised.
Data is stored in following format in Row Store:
1 Smith Joe 40000
2 Jones Mary 50000
3 Johnson Cathy 44000
Column Store on the other hand is Read-Optimised. Data is stored in the below format :
1 2 3
Smith Jones Johnson
Joe Mary Cathy
40000 50000 44000
This concept of Column Store is used in HANA, and which contributes to the high performance of reading data. One more advantage of Column Store data is stored in a compressed format as compared to Row Store. Also, its more efficient to calculate aggregate functions on columns.
You can refer : https://cookbook.experiencesaphana.com/what-is-bw-on-hana/technology-innovation/row-vs-column-based/ for a more detailed info.
Now, we get back to discuss the 2 scenarios. HANA Database can be used in 2 ways :
a. As a Primary Database
b. As a Secondary Database
b. As a Primary Database.
In this scenario, the SAP system will work on a single database i.e. the HANA database.
All read and inserts will happen on the HANA Database. This is used for BW systems.
c. As a Secondary Database.
In this scenario, HANA is used as Secondary Database, hence, SAP runs on dual database, where inserts happen on DB2 system and data is read from HANA database. This scenario can setup in R/3 systems. Here, the data is inserted in source system and is replicated on the HANA Database. This replication is near-realtime and is done through SLT (SAP Landscape Transformation) which migrates the source data by converting it to HANA enabled data.
*SLT : SAP LT Replication Server (SLT) is positioned for real-time data replication from SAP and non-SAP sources (SAP supported data bases only).
The data is replicated on the Persistence Storage, which in turn passes the data into the Main Memory (In-Memory) and is, therefore, available for reading.
In case, there is an issue reading from HANA Database, the ERP system can still read data from the ERP Database.
Do let me know if any doubts in these 2 scenarios. Will try cover the RDS and Native SQL in the next part.