rollbackdb

rollbackdb

A simple key/value database with fast rollback support.

npm install rollbackdb

Usage

var rollbackdb = require('rollbackdb')
// OBS: currently you have use the latest leveldown (>=1.2.0)
var db = require('levelup')('db', {db: require('leveldown')})

var rdb = rollbackdb(db)

rdb.put('hello', 'world', function () {
  var oldChange = rdb.changes
  console.log('added hello world at change', rdb.changes)
  rdb.put('hello', 'not world', function () {
    console.log('added hello not world at change', rdb.changes)
    rdb.get('hello', {version: oldChange}, console.log) // prints 'world'
  })
})

API

rdb = rollbackdb(levelup, [options])

Create a new rollbackdb instance. You can set version in options if you want to rollback the database to a previous version

checkoutRdb = rdb.checkout(version)

Shorthand for setting the version option in the constructor. Returns a new instance.

rdb.get(key, [options], cb)

Get a key. Set version in the options map to get the key that was added in a previous version of this database.

rdb.put(key, value, [cb])

Insert a key.

rdb.del(key, [cb])

Delete a key.

rdb.batch(batch, [cb])

Insert and/or deletes a batch of key/values

rdb.batch([{
  type: 'put',
  key: 'a',
  value: 'a'
}, {
  type: 'del',
  key: 'b',
  value: 'b'
}], function (err) {
  console.log('batch finished')
})

rdb.changes

A property containing the total number of changes/versions added to this database

rs = rdb.createChangesStream([options])

Returns a readable stream of all changes added to this database.

You can limit the range of changes returned by using the following options

{
  gt: changeNumber,
  gte: changeNumber,
  lt: changeNumber,
  lte: changeNumber
}

If you only want a single change stream returned set options.change = changeNumber

rs = rdb.createReadStream([options])

Create a readable stream of all keys and values in the database. Options include

{
  gt: 'keys-must-be-greater-than-me',
  gte: 'keys-must-be-greater-or-equal-to-me',
  lt: 'keys-must-be-less-than-me',
  lte: 'keys-must-be-less-or-equal-to-me',
  version: aVersionNumber // read all values in the database at this version
}

ws = rdb.createWriteStream()

Returns a writable stream that you can write {type: 'put'|'del', key: key, value: value} pairs to. All values written will be added to the same version.

License

MIT