https://github.com/doriantaylor/rb-rdf-lmdb

Symas (OpenLDAP) LMDB back-end for RDF::Repository
https://github.com/doriantaylor/rb-rdf-lmdb

database lmdb rdf

Last synced: 20 days ago
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Symas (OpenLDAP) LMDB back-end for RDF::Repository

• Host: GitHub
• URL: https://github.com/doriantaylor/rb-rdf-lmdb
• Owner: doriantaylor
• License: apache-2.0
• Created: 2019-09-08T05:03:38.000Z (over 5 years ago)
• Default Branch: main
• Last Pushed: 2024-10-09T22:09:13.000Z (3 months ago)
• Last Synced: 2024-11-16T15:38:48.233Z (about 2 months ago)
• Topics: database, lmdb, rdf
• Language: Ruby
• Homepage:
• Size: 36.1 KB
• Stars: 16
• Watchers: 6
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# RDF::LMDB - Lightweight, persistent, transactional RDF store

This library implements `RDF::Repository` using the Symas Lightning

MDB key-value database. It is intended to be a basic, durable,

locally-attached quad store, that avails itself of the properties of

LMDB.

`RDF::LMDB` is _also_ intended to provide a reference implementation

of an architecture for storing RDF in _any_ key-value database, such

that this adapter could be ported, or indeed the data _imported_, to

other back-ends (e.g. Berkeley DB, LevelDB, Kyoto Cabinet…) without

having to significantly change the design. The only real requirement

for the back-end is some kind of cursor functionality, and the

handling of multi-valued keys.

## Architecture

The system uses binary SHA-256 digests of N-Triples representations of

terms and statements. Terms are normalized first before being hashed.

The hashes themselves are stored in their binary representation.

### Triples

The main content of the store is keyed on the hash of a normalized

N-Triples statement (including the terminating ` .`). Its values are

the concatenated hashes of the individual terms:

    sha256(s  p  o " .") => sha256(s) sha256(p) sha256(o)

### GSPO

There are four indices that resolve terms to statements, _graph_,

_subject_, _predicate_, _object_, respectively:

    sha256(term) => sha256(s  p  o " .")

### Node Resolution

Finally, there is an index that maps the digests of the terms back to

their normalized N-Triples representations:

    sha256(term) => term

## API Documentation

Generated and deposited

[in the usual place](http://www.rubydoc.info/gems/rdf-lmdb/).

## Installation

Come on, you know how to do this:

    $ gem install rdf-lmdb

Or, [download it off rubygems.org](https://rubygems.org/gems/rdf-lmdb).

## Contributing

Bug reports and pull requests are welcome at

[the GitHub repository](https://github.com/doriantaylor/rb-rdf-sak).

## Copyright & License

©2019 [Dorian Taylor](https://doriantaylor.com/)

This software is provided under

the [Apache License, 2.0](https://www.apache.org/licenses/LICENSE-2.0).