https://github.com/mikpe/btree

B-tree storage of sets with configurable I/O, implemented in Erlang.
https://github.com/mikpe/btree

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B-tree storage of sets with configurable I/O, implemented in Erlang.

• Host: GitHub
• URL: https://github.com/mikpe/btree
• Owner: mikpe
• License: apache-2.0
• Created: 2016-12-07T16:53:56.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2024-07-05T15:46:57.000Z (6 months ago)
• Last Synced: 2024-07-05T20:58:34.151Z (6 months ago)
• Language: Erlang
• Size: 382 KB
• Stars: 11
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# btree

B-tree storage of sets with configurable I/O.

This implements B-trees of any order >= 2 in Erlang.

I/O is handled by user-provided callbacks.

Only sets (keys without data) are supported.

## Implementation notes

- Initially based on [Wirth76].

- Converted from Pascal to C, and then to Erlang.  The Erlang

  version uses tuples in lieu of arrays.  Pages are of variable

  not fixed size.

- I/O of pages is made explicit.

- Search is separated from insertion.  Search returns a stack of

  pages and indices recording the path from the root to the key.

  Insertion uses that stack to navigate the tree when rewriting it.

- Deletion is tricky enough that the recursive structure of the

  original code is kept as-is.  A local cache is used to avoid

  redundant I/O.

- Our use cases only want sets, so this does not associate

  attributes with the keys.

- Bulk-loading into an empty tree has been added.

## References

[BM72] R. Bayer and E. McCreight, "Organization and Maintenance of

Large Ordered Indexes", Acta Informatica, Vol. 1, Fasc. 3, pp. 173--189,

1972.

[Wirth76] Niklaus Wirth, "Algorithms + Data Structures = Programs",

Program 4.7, pp 252--257, Prentice-Hall, 1976.

[Comer79] Douglas Comer, "The Ubiquitous B-Tree", Computing Surveys,

Vol. 11, No. 2, pp 121--137, ACM, June 1979.