https://github.com/pietercolpaert/levelldf

Deprecated - Quick writes, quick triple pattern counts, quick triple pattern reads
https://github.com/pietercolpaert/levelldf

Last synced: 20 days ago
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Deprecated - Quick writes, quick triple pattern counts, quick triple pattern reads

• Host: GitHub
• URL: https://github.com/pietercolpaert/levelldf
• Owner: pietercolpaert
• Created: 2014-06-04T14:16:43.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2014-08-06T12:58:37.000Z (over 10 years ago)
• Last Synced: 2024-04-14T12:56:52.109Z (7 months ago)
• Language: JavaScript
• Homepage:
• Size: 184 KB
• Stars: 2
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# LevelLDF #

## Linked Data Fragments ##

A Linked Data Fragment (LDF) is a subset of elements in a Linked Data source that match a specific selector.

An LDF server serves Linked Data Fragments for specific selector classes through hypermedia.

## LevelLDF ##

LevelLDF resolves Basic Graph Patterns (BGP) in `O(n)`, with n the number of triples that match the BGP, and returns the number (count) of triples that match a certain BGP in `O(1)`.

LevelLDF uses LevelDB (a key value store) to store all triples using LevelGraph. It adds a second database which contains a hashed version of every possible BGP as a key and the count as a value. You can use LevelLDF to create your own LDF server, or to interface with a local LevelLDF database.

### Use the nodejs library###

#### getStream ####

```javascript

var ldf = require("levelldf");

ldf.getStream({predicate:"rdf:type"}).on("data", function ( triple ) {

  console.log(triple);

});

```

#### count ####

##### Performance

There's a script to test the performance of counts by comparing it to the wc bash command.

```bash

time -p ./test/performance.sh count

time -p ./test/performance.sh wc

```

#### putN3Stream ####

Pipe an n3 filestream in here

### Using the command line tool ###

When you got ldf in your $PATH, check out

```bash

ldf --help

ldf init

ldf import turtle.ttl

ldf bgp -p 'rdf:type'

ldf count -p 'rdf:type'

```