https://github.com/myui/btree4j

Disk-based B+-tree written in Pure Java
https://github.com/myui/btree4j

b-tree bplustree btree btree-indexes data-structures-and-algorithms disk indexing java

Last synced: about 2 months ago
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Disk-based B+-tree written in Pure Java

• Host: GitHub
• URL: https://github.com/myui/btree4j
• Owner: myui
• License: apache-2.0
• Created: 2017-12-12T09:30:24.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2020-10-13T00:46:36.000Z (almost 4 years ago)
• Last Synced: 2024-06-12T08:14:13.150Z (3 months ago)
• Topics: b-tree, bplustree, btree, btree-indexes, data-structures-and-algorithms, disk, indexing, java
• Language: Java
• Homepage:
• Size: 198 KB
• Stars: 211
• Watchers: 15
• Forks: 49
• Open Issues: 9
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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README

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

======================================================= 

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# What's Btree4j

Btree4j is a disk-based [Prefix B+-tree](https://dl.acm.org/citation.cfm?id=320530) written in Pure Java.

It's pretty fast and [100k ops/sec](https://github.com/myui/btree4j/blob/master/src/test/java/btree4j/benchmark/JMHBenchmark.java) is expected even on laptop.

# Using btree4j

```

    io.github.myui

    btree4j

    0.9.1

```

[Find usage](https://github.com/myui/btree4j/tree/master/src/test/java/btree4j) in unit tests.

# Features and Strength

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

* Implementes [Prefix B+-tree](https://dl.acm.org/citation.cfm?id=320530) in which prefixes are selected carefully to minimize their length. In prefix B+-tree, key prefixes are managed by a [TRIE](https://en.wikipedia.org/wiki/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](https://doi.org/10.1145/320521.320530 )]

* Pointers are [compressed](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/utils/codec/VariableByteCodec.java) using [Variable Byte Codes](https://en.wikipedia.org/wiki/Variable-length_code) 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](https://en.wikipedia.org/wiki/Indexed_file) based on B+-tree is [supported](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/BTreeIndex.java). [Multiple values per a key](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/BTreeIndexDup.java) is also supported.

 [BTreeIndex](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/BTreeIndex.java) stores `` with VALUE stored on distinct data pages and pointers to them are managed by [B+-Tree](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/BTree.java) to avoid consuming many disk pages for large values in B+-tree.

* Support variable-length [key](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/Key.java)/[value](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/Value.java)

* [Prefix and range search](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/indexer/BasicIndexQuery.java) is supported in addition to exact match using a [flexible callback handler](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/BTreeCallback.java). Support [LIKE match](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/indexer/LikeIndexQuery.java) using wildcards.

* Paging (virtual memory) support using [LRU cache replacement policy](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/BTree.java) and [Freespace management](https://github.com/myui/btree4j/blob/master/src/main/java/btree4j/FreeList.java).

* 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](https://github.com/myui/xbird/) based on [Apache Xindice](https://xml.apache.org/xindice/dev/guide-internals.html#3.+Data+storage).