The solidDB^® main memory engine combines the high performance of in-memory tables along with the nearly unlimited capacity of disk-based tables. Pure in‑memory databases are fast, but strictly limited by the size of memory. Pure disk‑based databases allow nearly unlimited amounts of storage, but their performance is dominated by disk access. Even if the computer has enough memory to store the entire database in memory buffers, database servers designed for disk-based tables can be slow because the data structures that are optimal for disk-based tables are far from being optimal for in-memory tables.

The solidDB^® solution is to provide a single database server that contains two optimized servers inside it: one server is optimized for disk-based access and the other is optimized for in-memory access. Both servers coexist inside the same process, and a single SQL statement may access data from both engines.