Database Reference
In-Depth Information
Local persistence store
DynamoDB's local persistence store is a pluggable system where you can select the storage
depending upon the application use. Generally, DynamoDB uses Berkeley DB or MySQL
as the local persistence store. Berkeley DB is a high-performance embedded database lib-
rary used for key-value pair type of storage. The storage is selected depending upon the ap-
plication object size. Berkeley DB is used where object size has a maximum limit of 10
KB, while MySQL is used for application object size expected to be on the higher side.
Most of Amazon's production systems use Berkeley DB as their local storage. As an AWS
customer, we don't have the choice to select our local persistence store though.
Berkeley DB is a library that is used as embedded data storage. It is written in C language
and provides APIs to various languages, such as Java, C++, PHP, C#, and so on. It stores
data in the key value format. The initial version of Berkeley DB was out way back in 1994;
since then, it has seen many changes and upgrades. Currently, it is in development at
Oracle Corporation.
Berkeley DB has three products under one umbrella, which are as follows:
• Berkeley DB, which is a traditional library written in C
• Berkeley DB Java Edition, which supports important Java features, such as POJOs,
Collections, and so on
• Berkeley DB XML edition, which supports data storage of XML documents
Berkley DB provides local storage, underlying storage and retrieval for many databases,
LDAP servers like MySQL, Oracle NoSQL, Subversion (SVN), MemcacheDB, RPM, and
many more.
