What type of data is primarily affected by delta merges?

Delta merges primarily affect transactional data in a database, especially within the context of an in-memory database like SAP HANA. Transactional data is often subject to frequent changes, inserts, and deletes, reflecting real-time business operations.

In HANA, transactional data accumulates in delta storage as changes occur. Over time, this delta storage can become large if not managed. A delta merge operation is a process that consolidates the delta storage with the main (or persistent) storage, optimizing performance by ensuring that the active dataset reflects the most current state of the data. This process is crucial for maintaining system efficiency and ensuring that queries run against the latest information.

Static data and historical data, while relevant in a database context, typically experience less frequent updates, meaning delta merges would have minimal impact on them. Metadata provides information about the structure and organization of data, but it does not change in the same way as transactional data. Therefore, it is transactional data that is most directly and significantly affected by delta merges in HANA.