What is an In-Memory Database?
What is a Hybrid Database?
A hybrid database (Hybrid DB) is a database management system that is a balanced database management system that offers high performance data processing in main memory with the vast storage capabilities of physical disk. A hybrid database has both in-memory database features and on-disk database features in a single unified engine. As a result, data can be stored and manipulated in main memory alone, on physical disk alone or a combination of both. The integrated combination of both database types allows for unrivaled flexibility and robust functionality. For example, Altibase was the first commercially available true hybrid database tn the world and has been fortified with over 17 years of enterprise experience. Click for details on advanced features and functionality.
What are Caching and an On-Disk Database?
An on-disk database is traditionally a general-purpose database management system that follows a relational model. It stores and manipulates data on physical disk. The database landscape is changing and traditional on-disk databases are rapidly becoming legacy systems. The reason is that on-disk databases are slowed by disk I/O. Caching temporarily maintains frequently accessed data in-memory and, as such, it is commonly misconstrued as being an in-memory database or hybrid database. Caching, in stark contrast to an in-memory database, is only fast for reads while data manipulation such as INSERT, UPDATE and DELETE is still subject to the sluggishness of normal disk I/O.
What happens to my data in memory if there is a power failure?
In-memory (RAM) is, by definition, volatile. As such, if there is a power failure, in theory you can lose data in-memory. Considering the volatile nature of RAM, Altibase provides many different kinds of durability methods to guarantee data preservation. When data is changed, a log of that transaction is written to a reserved RAM space, and those logs are periodically flushed to disk. Once those logs reach a certain size, a datafile is written as a second backup. Altibase also provides replication built into the engine itself, which guarantees not only data integrity, but also application availability. Altibase can also ensure strict durability to maintain complete data integrity by utilizing its Storage Manager module to prevent any data loss. Simply, through its hybrid architecture, once a transaction is committed, COMMIT must occur with success on physical disk which results in 100% data integrity. Finally, there is non-volatile memory, NVRAM, that in essence has a battery backup (that kicks in if there is a power failure) that can maintain data in the event of a power loss.