SAP / SAP Mid Level (3 to 8 yrs) Interview questions
What is SAP HANA and why is it described as an in-memory database?
SAP HANA (High-performance ANalytic Appliance) is SAP's proprietary database platform that keeps the primary copy of data resident in RAM rather than treating disk as the main storage medium the way traditional databases do — disk is still used for persistence (so data survives a restart), but the data actively being read and written lives in memory.
flowchart LR
A[Application query] --> B[HANA in-memory engine - data resident in RAM]
B --> C[Result returned, typically in milliseconds]
B -.persisted asynchronously.-> D[Disk - for durability/restart]
Since RAM access is orders of magnitude faster than disk I/O, this eliminates the traditional bottleneck of waiting on disk reads for every query, which is what lets HANA run complex analytical queries against large datasets in near real time — a workload that would require pre-aggregated reporting tables or overnight batch jobs on a disk-based system.
Where does SAP HANA keep the primary, actively-used copy of data?
What traditional bottleneck does in-memory processing eliminate?
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