Awesome

PrefixDOWN

LevelDB sections using key prefix as a LevelUP backend.

npm install prefixdown

By exposing a LevelDOWN compatible module, PrefixDOWN does not modify, nor set a wrapper on top of current LevelUP instance. So that it can be used on any existing LevelUP based libraries.

levelup(prefix, { db: prefixdown, levelup: db })

levelup(prefix, { db: prefixdown(db) })

PrefixDOWN on top of LevelUP, where location argument defines the prefix.

var levelup = require('levelup')
var prefixdown = require('prefixdown')

var db = levelup('./db') //root levelup instance

//location as prefix
var dbA = levelup('!a!', { db: prefixdown, levelup: db })
var dbB = levelup('!b!', { db: prefixdown(db) })

dbA.put('foo', 'hello', function () {
  dbB.put('foo', 'world', function () {
    db.createReadStream().on('data', ...)
    //Results from root db
    //{key: '!a!foo', value: 'hello'}
    //{key: '!b!foo', value: 'world'}
  })
})

options.prefix

PrefixDOWN supports options.prefix property. A batch operation can be applied into multiple sections under the same database.

var dbA = levelup('!a!', { db: prefixdown, levelup: db })
var dbB = levelup('!b!', { db: prefixdown, levelup: db })

dbA.batch([
  {key: 'foo', value: 'a', type: 'put'},
  {key: 'foo', value: 'b', type: 'put', prefix: dbB } // options.prefix
], function (err) {
  dbA.get('foo', function (err, val) {
    console.log(val) // a
  });
  dbB.get('foo', function (err, val) {
    console.log(val) // b
  });
})

License

MIT