"...since caching is available, why not extend its use
to cache entire databases to realize desired performance gains? In
addition, RAM-drive utilities exist to create file systems in
memory. Deploying a traditional database on such a RAM-disk
eliminates physical disk access entirely. Shouldn't its performance
equal the main memory database?
...To examine this question, McObject recently benchmarked three
approaches to data management. The first used db.linux, a
disk-based DBMS, in the traditional fashion, with caching as the
only means for reducing disk I/O. The second test differed only in
deploying db.linux on a RAM-disk. For the third, application and
database design were held constant, but the disk-based database was
replaced by McObject's eXtremeDB main memory database.
The open source db.linux was chosen as a representative
disk-based database, due to its longevity (first released in 1986
under the name db_VISTA) and also to the author's familiarity with
its usage in several Internet-enabled device applications.
Technically, eXtremeDB and db.linux presented an "apples to apples"
comparison. They have similar database definition languages and are
designed to be embedded in applications rather than provide a
separately administered server, like Microsoft SQL Server or
Oracle. Each has a relatively small footprint when compared to
enterprise class databases, and offers a navigational API for
precise control over database operations."