btree4j: Disk-based Prefix B+-tree written in Pure Java

What's Btree4j

Btree4j is a disk-based Prefix B+-tree written in Pure Java.

It's pretty fast and 100k ops/sec is expected even on laptop.

Using btree4j

<dependency>
    <groupId>io.github.myui</groupId>
    <artifactId>btree4j</artifactId>
    <version>0.9.1</version>
</dependency>

Find usage in unit tests.

Features and Strength

Applied many improvements over the original Xindice's implementation as follows:

• Implementes Prefix B+-tree in which prefixes are selected carefully to minimize their length. In prefix B+-tree, key prefixes are managed by a TRIE-like smart algorithm.

Rudolf Bayer and Karl Unterauer. "Prefix B-trees", Proc. ACM Trans. Database Syst. 2, 1, pp.11-26), March 1977. [DOI]

• Pointers are compressed using Variable Byte Codes so that more keys/values are fit in memory.

• Support both unique and non-unique indexing. Storing duplicate keys is allowed for non-unique indexing.

• Index file based on B+-tree is supported. Multiple values per a key is also supported. BTreeIndex stores <bytes[] KEY, byte[] VALUE> with VALUE stored on distinct data pages and pointers to them are managed by B+-Tree to avoid consuming many disk pages for large values in B+-tree.

• Support variable-length key/value

• Prefix and range search is supported in addition to exact match using a flexible callback handler. Support LIKE match using wildcards.

• Paging (virtual memory) support using LRU cache replacement policy and Freespace management.

• Deletion and updates are, of course, supported.

• Support efficient Bulk-loading.

• Minimum dependencies to external libraries. Runs on Java 8 or later.

Sponsors

No sponsors yet. Will you be the first?

It will be my motivation to continue working on this project.

Credits

Copyright 2006 and onwards Makoto Yui
Copyright 1999-2007 The Apache Software Foundation

This software is originally developed for XBird based on Apache Xindice.