Storing data – row storage

As seen in the architectural diagram of SAP HANA IMCE, there are two relational engines in the heart of the IMCE. These relational engines are in-memory, meaning that their primary data persistence is based in RAM. The row store stores the data in rows, and in this respect, it behaves like a traditional database—except that the data always resides in RAM. The row store engine is highly optimized for write operations and is interfaced from the calculation/execution layer. All the operations on the row tables will be processed by this row engine. When a query is fired on to the SAP HANA database, the optimizer decides in which engine the query has to be executed. For example, there may be some functions that OLAP engine doesn't support, but the row engine does. In that case, the optimizer sends all the data to the row engine and gets the task done. This may be more expensive as the column data has to be converted to row data before it is processed...