level-sum

Calculate multidimensional sums in a LevelDB and get live updates.

Example

Store and retrieve visit counts and query by multiple dimensions:

var level = require('level');
var sub = require('level-sublevel');
var Sum = require('level-sum');

var db = sub(level(__dirname + '/db'));
var sum = Sum(db);

sum.follow(['visits']).on('data', function(visits) {
  console.log('all visits: %s', visits);
  // all visits: 1
  // all visits: 2
  // all visits: 4
});

sum.follow(['visits', 'home']).on('data', function(visits) {
  console.log('home visits: %s', visits);
  // home visits: 1
  // home visits: 3
});

sum.incr(['visits', 'home']);
setTimeout(function() { sum.incr(['visits', 'profile']) }, 1000);
setTimeout(function() { sum.incr(['visits', 'home'], 2) }, 2000);

API

Sum(db)

Create a new sums db. Make sure your db has been given the powers of level-sublevel.

Sum#incr(key[, amount][, fn])

Increment the sum key by amount or 1 and optionally call fn when done, with a possible error.

key can be a string or array of strings.

Sum#get(key, fn)

Get the current sum for key, which can be a string or array of strings.

Sum#follow(key)

Create a readable stream that emits the initial value as well as following updates to it. key can be a string or array of strings.

Installation

With npm do:

npm install level-sum

License

(MIT)

Copyright (c) 2013 Julian Gruber <julian@juliangruber.com>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.