In-memory and Persistent Database Management Systems

What is a persistent database, and how is it different?  The answer below explains first what an in-memory database is, then, in the next paragraph, how a persistent database differs. 

Simple architecture of in-memory database system.

What is a persistent database system?

In contrast, on-disk or persistent database systems cache frequently requested data in memory for faster access, but write database updates, insertions and deletes through the cache to be stored to disk. On the plus side, byte-for-byte, disk storage can be cheaper than RAM, and can also take less physical space when form factor is a consideration (e.g. handheld electronics).

Using a true in-memory database system is critical to getting all the benefits from a hybrid solution. Understanding the distinction is critical to determining the performance, cost and ultimately the success or failure of a solution.  Learn how to tell the difference between real and imitation in-memory database systems, and why it matters in our white paper: Will the Real IMDS Please Stand Up?

An in-memory database with transaction logging retains the high performance read characteristics and provides tune-able persistence while retaining much of the in-memory database insert/update/delete performance advantage.

eXtremeDB offers these options.  Learn more about our hybrid database options.

In-memory and persistent database systems can be either embedded or client/server. 

Learn more about the eXtremeDB in-memory and persistent database management system.