RedisDOWN

Redis backend for LevelUP

Requirements:

• redis-2.8 or more recent.
• node-12.x

Uses a sorted-set to order the keys and a hash to store the values.

Fetches the ordered key value pairs during iterations with a single redis lua call.

Abstract-LevelDOWN testsuite is green except for the 'implicit iterator snapshot'.

Warning: data migration from redisdown-v0.1.9

redisdown > v0.1.10 no longer JSON encode/decode itself. Levelup take care of that. JSON Data written in v0.1.9 is not correctly decoded back to a javascript object in v0.1.10 and above.

This change was introduced to support binary values in redisdown and escaped the fact that it was breaking backward compatibility for the data.

Workaround: #24 (comment)

Example

Copied and pasted from the levelup documentation. Added the db option when creating the db to use redisdown.

var levelup = require('levelup')
var redisdown = require('redisdown')

// 1) Create our database, supply location and options.
//    This will create or open the underlying LevelDB store.
var db = levelup('mydb', { db: redisdown, host: 'localhost', port: 6379 })

// If you use sentinel/cluster mode, you must use a single slot to store the values thanks to a `{hash}`
//var db = levelup('{thehash}path', { db: redisdown });

// if you already have a redis client
//var db = levelup('mydb', { db: redisdown, redis: redisClient })

// if you use an URL environment variable
//var db = levelup('mydb', { db: redisdown, url: process.env.REDIS_URL })
// if you use Redis Cloud on Heroku
//var db = levelup('mydb', { db: redisdown, url: process.env.REDISCLOUD_URL })

// 2) put a key & value
db.put('name', 'LevelUP', function (err) {
  if (err) return console.log('Ooops!', err) // some kind of I/O error

  // 3) fetch by key
  db.get('name', function (err, value) {
    if (err) return console.log('Ooops!', err) // likely the key was not found

    // ta da!
    console.log('name=' + value)
  })
})

API

---

redisdown(location)

redisdown(location) returns a new RedisDOWN instance. location is a String pointing at the root namespace of the data in redis.

• location+':h' is the hash where the values are stored.
• location+':z' is the set where the keys are sorted.

---

redisdown#open([options, ]callback)

open() is an instance method on an existing database object.

options is a hash that is passed to the redis library to create a redis client:

• highWaterMark number of values to fetch in one redis call for iteration. Defaults to 256.
• port redis port. Defaults to '127.0.0.1'
• host redis host. Defaults to 6379
• redis already configured redis client. redisDown will not open or close it. host and port and all other redis options are ignored.
• Other options: https://github.com/mranney/node_redis#rediscreateclientport-host-options

---

redisdown.destroy(location, [options, ]callback)

destroy(location) is used to completely delete all data in redis related to the location.

---

redisdown#batch([{type: 'put', key: 'foo1', value: 'bar1' [, prefix: 'subsection']}, ...])

batch() supports an exra property prefix to store/retrieve/delete a key in a specific namespace of the redis DB. It is useful to support sublevel-ish batch operations: https://github.com/dominictarr/level-sublevel#batches and is well supported by redis.

By default, the prefix is a string that is the path to the where redis stores the document. In order to resolve other types of prefixes, one would need to override the #__getPrefix(prefix) method. Passing a levelup instance is demonstrated here: https://github.com/hmalphettes/redisdown/blob/master/test/batch-prefix-test.js#L12

Pouchdb integrations tests: all 3605 of them

---

npm run-script test-pouchdb-redis

The script will install the extra required dependencies. It works for me.

LICENSE

redisdown is freely distributable under the term of the MIT License. Copyright: Sutoiku Inc 2014.

If you need something different, let me know.

HELP Wanted

• Collation: do we need to worry about this?