WiredTiger

WiredTiger is an open-source key/value storage engine for NoSQL databases and is currently the default storage engine for MongoDB.

WiredTiger supports both B-tree and log-structured merge tree for data storage. It also supports both row store and column store. WiredTiger employs multi-version concurrency control for better scalability on multi-core architectures and supports several standard isolation levels. Though WiredTiger is often considered as a storage engine, it also has some basic schema support where schemas are provided by users at runtime.

WiredTiger is developed in C and provides Java/Python language bindings. It has a set of APIs that is compatible with LevelDB.

System Architecture

Embedded

Indexes

B+Tree

Storage Architecture

Disk-oriented