Kai

View Current Viewing Revision #8 from 11/24/2019 11:38 p.m.

Kai is a open-source distributed key-value database, which is inspired by Amazon's Dynamo. Same as DynamoDB, it is developed for high scalability and validity of Web sites. goo home, a Japanese social networking service of more than 10 million users, is using Kai as a successful example of Kai. Because it is hard to get the search result of the Kai database through the current Web search Engine. It is suggested to search Kai with another keyword, such as erlang, sourceforge, or dynamo.

History

The Kai open-source project started in May 2008 and hosted on sourceforge.net. By May of 2009, 4 versions were released and the latest version is Kai-0.4.0. Most of the developers involved in the project were from Japan and the name of Kai is from the name of one of the developers' hometown.

Data Model

Key/Value

Kai uses a key/value data model. Any value(bit-string) can be stored with a key, which is used to retrieve the value.

System Architecture

Shared-Nothing

Kas's system architecture is based on a distributed hash table, a peer-to-peer distributed system architecture. The storage capacity of the cluster can be roughly determined by the number of nodes in the cluster so the distributed structure enables the system to scale up and down based on the required capacity. To organize cluster nodes, epidemic protocol is used to spread the membership information.

Storage Organization

Heaps

Kas's storage organization is based on a distributed hash table, a peer-to-peer distributed system architecture. The storage capacity of the cluster can be roughly determined by the number of nodes in the cluster so the distributed structure enables the system to scale up and down based on the required capacity. To organize cluster nodes, epidemic protocol is used to spread the membership information.

Query Interface

Custom API

Kai supports basic operations(not all) of memcache API, including get(s), set, delete, quit and version. However, users cannot specify the operations' expiration time, all operation results is persistent.

Storage Architecture

Disk-oriented

Same as Amazon DynamoDB, Kai provides consistent storage in cache. It uses disk-oriented storage architecture.

Parallel Execution

Bushy

The distributed structure makes Kai's requests will be distributed to N nodes in parallel. Kai uses actor model, which supported by Erlang, to collaborate with each processes with each other. One advantage of actor model is that it does not rely on shared memory, which often causes painful bugs.

Revision #8 | Updated 11/24/2019 11:38 p.m.