In what scenario would a system perform a delta merge?

A delta merge occurs primarily to optimize the storage and performance of the in-memory database, particularly within the context of HANA's column store. The process of a delta merge is triggered when the memory utilization reaches a specific threshold, indicating that the system can benefit from consolidating the main and delta storage areas.

In HANA, data is initially written to a delta storage area to ensure low latency for insert operations. However, when memory usage becomes high, the system will perform a delta merge to transfer the data from the delta area back into the main storage area, thus freeing up memory and optimizing performance. This ensures that the main store operates efficiently by reducing the fragmentation of data and allowing more effective data retrieval operations.

The other scenarios presented do not inherently trigger a delta merge. While archiving large data volumes or performing updates may have an impact on data management, these activities do not directly relate to memory thresholds or management strategies that necessitate a delta merge. Periodic merges might occur under certain maintenance routines but are not inherently tied to memory performance in the same way that managing memory usage is.