CBForest is a C++ wrapper around ForestDB, a new key-value storage engine based on a hierarchical B+-tree trie data structure. ForestDB is similar in functionality to the CouchStore engine that currently underlies Couchbase Server, but it should be faster and more space-efficient, especially on solid-state disks (SSDs). CBForest adds an idiomatic object-oriented C++ API for ForestDB, and also some new functionality (see below.)
The immediate purpose of CBForest is to serve as the storage engine of the next generation of Couchbase Lite (on all platforms), replacing SQLite. But it may find other uses too, perhaps for applications that want a fast minimalist data store but don't need any of the fancy features of Couchbase Lite like replication.
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ForestDB features, available via an idiomatic C++ API:
- Fast key-value storage, where keys and values are both opaque blobs.
- Extremely robust append-only file format with write-ahead log.
- Reads are never blocked, even while writes or transactions are in progress.
- Iteration by key order.
- Iteration by sequence, reflecting the order in which changes were made to the database. (This is useful for tasks like updating indexes and replication.)
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New features implemented by CBForest:
- Optional multi-version document format that keeps a revision tree of the history of each document (as in Couchbase Lite or CouchDB.)
- Index API that uses a database as an index of an external data set.
- Map-reduce indexes that update incrementally as documents are changed in the source DB (as in Couchbase Lite or CouchDB.)
- Support for JSON-compatible structured keys in indexes, sorted according to CouchDB's JSON collation spec.
CBForest is intended to run on Mac OS, iOS, Android, various other flavors of Unix, and Windows.
However, it's currently [as of July 2014] only been used or tested on Mac OS and iOS, so there might be inadvertent platform dependencies. Please report any issues you find on other platforms.
Like all Couchbase source code, this is released under the Apache 2 license.