When storing data with an in-memory database, a distinction is made between column-oriented and row-oriented data storage, whereby some database systems use both methods of data storage. Row-oriented databases arrange the collected data records together in one row. For example, if the values “name, city, and country” are stored, the data would be arranged as follows: name 1, city 1, country 1, name 2, city 2, country 2. In a column-based storage, the data is assigned to its corresponding categories in this way: name 1, name 2, city 1, city 2, country 1, country 2.
The storage format for column-based data storage is called columnar format. By storing data with identical values together, the system minimizes the number of existing data. Storage space and transmission times are therefore reduced. The analysis performance of in-memory databases has also improved over time, seeing as only specific columns need to be analyzed, and not all of them. This form of data evaluation is called columnar projection.