Distributed scalable database.
npm install hyperdb
Read ARCHITECTURE.md for details on how hyperdb works.
var hyperdb = require('hyperdb')
var db = hyperdb('./my.db', {valueEncoding: 'utf-8'})
db.put('/hello', 'world', function (err) {
if (err) throw err
db.get('/hello', function (err, nodes) {
if (err) throw err
console.log('/hello --> ' + nodes[0].value)
})
})Create a new hyperdb.
storage can be a string or a function. If a string like the above example, the
random-access-file storage
module is used; the resulting folder with the data will be whatever storage is
set to.
If storage is a function, it will be called with every filename hyperdb needs
to operate on. There are many providers for the
abstract-random-access
interface. e.g.
var ram = require('random-access-memory')
var feed = hyperdb(function (filename) {
// filename will be one of: data, bitfield, tree, signatures, key, secret_key
// the data file will contain all your data concattenated.
// just store all files in ram by returning a random-access-memory instance
return ram()
})key is a Buffer containing the local feed's public key. If you do not set
this the public key will be loaded from storage. If no key exists a new key pair
will be generated.
Options include:
{
map: node => mappedNode, // map nodes before returning them
reduce: (a, b) => someNode, // reduce the nodes array before returning it
firstNode: false, // set to true to reduce the nodes array to the first node in it
valueEncoding: 'binary' // set the value encoding of the db
}Buffer containing the public key identifying this hyperdb.
Populated after ready has been emitted. May be null before the event.
Buffer containing a key derived from the db.key.
In contrast to db.key this key does not allow you to verify the data but can be used to announce or look for peers that are sharing the same hyperdb, without leaking the hyperdb key.
Populated after ready has been emitted. May be null before the event.
Emitted exactly once: when the db is fully ready and all static properties have been set. You do not need to wait for this when calling any async functions.
Get the current version identifier as a buffer for the db.
Checkout the db at an older version. The checkout is a DB instance as well.
Version should be a version identifier returned by the db.version api or an
array of nodes returned from db.heads.
Insert a new value. Will merge any previous values seen for this key.
Lookup a string key. Returns a nodes array with the current values for this key.
If there is no current conflicts for this key the array will only contain a single node.
Delete a string key.
Insert a batch of values efficiently, in a single atomic transaction. A batch should be an array of objects that look like this:
{
type: 'put',
key: someKey,
value: someValue
}callback's parameters are err, nodes, where nodes is an array of the batched nodes.
Your local writable feed. You have to get an owner of the hyperdb to authorize you to have your writes replicate. The first person to create the hyperdb is the first owner.
Authorize another peer to write to the hyperdb.
To get another peer to authorize you you'd usually do something like
myDb.on('ready', function () {
console.log('You local key is ' + myDb.local.key.toString('hex'))
console.log('Tell an owner to authorize it')
})Check whether a key is authorized to write to the database.
myDb.authorized(otherDb.local.key, function (err, auth) {
if (err) console.log('err', err)
else if (auth === true) console.log('authorized')
else console.log('not authorized')
})Watch a folder and get notified anytime a key inside this folder has changed.
db.watch('foo/bar', function () {
console.log('folder has changed')
})
...
db.put('foo/bar/baz', 'hi') // triggers the aboveYou can destroy the watcher by calling watcher.destroy().
The watcher will emit watching when it starts watching and change
when a change has been detected.
If a critical error occurs an error will be emitted on the watcher.
Create a readable stream of nodes stored in the database.
Set prefix to only iterate nodes prefixed with that folder.
Options include:
{
recursive: true // visit all subfolders.
// set to false to only visit the first node in each folder
reverse: true // read the records in reverse order.
gt: false // visit only strictly nodes that are > than the prefix
}Create a writable stream.
Where stream.write(data) accepts data as an object or an array of objects with the same form as db.batch().
Same as createReadStream but buffers the result to a list that is passed to the
callback.
Find out about changes in key/value pairs between the version checkout and
current version prefixed by prefix.
stream is a readable object stream that outputs modifications like
{ left: nodes, right: nodes }left are the nodes for a key found in the db and right are the nodes found in the checkout.
If no nodes exist in the db for the key left will be null and vice versa.
Returns a readable stream of node objects covering all historic values since the beginning of time.
Nodes are emitted in topographic order, meaning if value v2 was aware of value
v1 at its insertion time, v1 must be emitted before v2.
To emit the nodes in reverse order pass {reverse: true} as an option.
Returns a readable stream of node objects covering all historic values for a specific key.
Results are returned with the latest value first.
Create a replication stream. Options include:
{
live: false // set to true to keep replicating
}MIT