SAP / SAP Mid Level (3 to 8 yrs) Interview questions
Explain the difference between row store and column store in HANA?
HANA supports both storage layouts, and choosing between them matters for performance depending on how data is typically queried.
| Row Store | Column Store |
| Data physically stored row by row, all fields of a row together. | Data physically stored column by column, all values of one field together. |
| Efficient for retrieving/writing a whole record at once (OLTP-style). | Efficient for scanning/aggregating one or a few columns across many rows (OLAP-style). |
| Better fit for small, transactional tables. | Better fit for large tables with analytical, aggregate-heavy queries. |
-- column store shines here: scanning just the `amount` and `region` columns -- across millions of rows, ignoring every other field entirely SELECT region, SUM(amount) FROM sales_transactions GROUP BY region;
HANA's default and predominant storage for most business tables is column store, since analytical, aggregate-style access patterns are extremely common in ERP reporting, but row store remains available and appropriate for specific tables where whole-row access dominates.
How is data physically organized in column store, compared to row store?
Which storage layout is generally better for aggregate-heavy analytical queries?
More Related questions...
