rethinkdbdash
A Node.js driver for RethinkDB with more advanced features.
Install
npm install rethinkdbdash
Note: The rethinkdbdash-unstable
package is a relic from the past (rethinkdb < 1.13).
Quick start
Rethinkdbdash uses almost the same API as the official driver. Please refer to
the official driver's documentation
for all the ReQL methods (the methods used to build the query).
The main differences are:
- You need to execute the module when you import it:
var r = require('rethinkdbdash')();
- Connections are managed by the driver with an efficient connection pool.
Once you have imported the driver, you can immediately run queries,
you don't need to call
r.connect
, or pass a connection to run
.
var r = require('rethinkdbdash')();
r.table('users').get('orphee@gmail.com').run().then(function(user) {
}).error(handleError)
- Cursors are coerced to arrays by default
var r = require('rethinkdbdash')();
r.table('data').run().then(function(result) {
assert(Array.isArray(result))
});
Drop in
You can replace the official driver with rethinkdbdash by just replacing
var r = require('rethinkdb');
With:
var r = require('rethinkdbdash')({
pool: false,
cursor: true
});
If you want to take advantage of the connection pool, refer to the next section.
From the official driver
To switch from the official driver to rethinkdbdash and get the most of it,
here are the few things to do:
- Change the way to import the driver.
var r = require('rethinkdb');
To:
var r = require('rethinkdbdash')();
- Remove everything related to a connection:
r.connect({host: ..., port: ...}).then(function(connection) {
connection.on('error', handleError);
query.run(connection).then(function(result) {
connection.close();
});
});
Becomes:
query.run().then(function(result) {
});
- Remove the methods related to the cursor. This typically involves
removing
toArray
:
r.table('data').run(connection).then(function(cursor) {
cursor.toArray().then(function(result) {
});
});
Becomes
r.table('data').run().then(function(result) {
});
New features and differences
Rethinkdbdash ships with a few interesting features.
Importing the driver
When you import the driver, as soon as you execute the module, you will create
a default connection pool (except if you pass {pool: false}
. The options you
can pass are:
db
: <string>
- The default database to use if none is mentioned.discovery
: <boolean>
- When true, the driver will regularly pull data from the table server_status
to
keep a list of updated hosts, default false
pool
: <boolean>
- Set it to false
, if you do not want to use a connection pool.buffer
: <number>
- Minimum number of connections available in the pool, default 50
max
: ``- Maximum number of connections available in the pool, default
1000`timeout
: <number> - The number of seconds for a connection to be opened, default
20`timeoutError
: ` - Wait time before reconnecting in case of an error (in ms), default 1000timeoutGb
: <number>
- How long the pool keep a connection that hasn't been used (in ms), default 60601000maxExponent
: <number>
- The maximum timeout before trying to reconnect is 2^maxExponent x timeoutError, default 6 (~60 seconds for the longest wait)silent
: - console.error errors, default false
servers
: an of objects {host: <string>, port: <number>}
representing instances of
RethinkDB to connect to.
In case of a single instance, you can directly pass host
and port
in the top level parameters.
Examples:
// connect to localhost:8080, and let the driver find other instances
var r = require('rethinkdbdash')({
discovery: true
});
// connect to and only to localhost:8080
var r = require('rethinkdbdash')();
// Do not create a connection pool
var r = require('rethinkdbdash')({pool: false});
// Connect to a cluster seeding from `192.168.0.100`, `192.168.0.100`, `192.168.0.102`
var r = require('rethinkdbdash')({
servers: [
{host: '192.168.0.100', port: 28015},
{host: '192.168.0.101', port: 28015},
{host: '192.168.0.102', port: 28015},
]
});
// Connect to a cluster containing `192.168.0.100`, `192.168.0.100`, `192.168.0.102` and
use a maximum of 3000 connections and try to keep 300 connections available at all time.
var r = require('rethinkdbdash')({
servers: [
{host: '192.168.0.100', port: 28015},
{host: '192.168.0.101', port: 28015},
{host: '192.168.0.102', port: 28015},
],
buffer: 300,
max: 3000
});
You can also pass {cursor: true}
if you want to retrieve RethinkDB streams as cursors
and not arrays by default.
Note: The option {stream: true}
that asynchronously returns a stream is deprecated. Use toStream
instead.
Connection pool
As mentionned before, rethinkdbdash
has a connection pool and manage all the connections
itself. The connection pool is initialized as soon as you execute the module.
You should never have to worry about connections in rethinkdbdash. Connections are created
as they are needed, and in case of a host failure, the pool will try to open connections with an
exponential back off algorithm.
The driver execute one query per connection. Now that rethinkdb/rethinkdb#3296
is solved, this behavior may be changed in the future.
Because the connection pool will keep some connections available, a script will not
terminate. If you have finished executing your queries and want your Node.js script
to exit, you need to drain the pool with:
r.getPoolMaster().drain();
Advanced details about the pool
The pool is composed of a PoolMaster
that retrieve connections for n
pools where n
is the number of
servers the driver is connected to. Each pool is connected to a unique host.
To access the pool master, you can call the method r.getPoolMaster()
.
The pool emits a few events:
draining
: when drain
is calledqueueing
: when a query is added/removed from the queue (queries waiting for a connection), the size of the queue is providedsize
: when the number of connections changes, the number of connections is providedavailable-size
: when the number of available connections changes, the number of available connections is provided
You can get the number of connections (opened or being opened).
r.getPoolMaster().getLength();
You can also get the number of available connections (idle connections, without
a query running on it).
r.getPoolMaster().getAvailableLength();
You can also drain the pool as mentionned earlier with;
r.getPoolMaster().drain();
You can access all the pools with:
r.getPoolMaster().getPools();
Note about connections
If you do not wish to use rethinkdbdash connection pool, you can implement yours. The
connections created with rethinkdbdash emits a "release" event when they receive an
error, an atom, or the end (or full) sequence.
A connection can also emit a "timeout" event if the underlying connection times out.
Arrays by default, not cursors
Rethinkdbdash automatically coerce cursors to arrays. If you need a raw cursor,
you can call the run
command with the option {cursor: true}
or import the
driver with {cursor: true}
.
r.expr([1, 2, 3]).run().then(function(result) {
console.log(JSON.stringify(result))
})
r.expr([1, 2, 3]).run({cursor: true}).then(function(result) {
cursor.toArray().then(function(result) {
console.log(JSON.stringify(result))
});
})
Note: If a query returns a cursor, the connection will not be
released as long as the cursor hasn't fetched everything or has been closed.
Readable streams
Readable streams can be
synchronously returned with the toStream([connection])
method.
var fs = require('fs');
var file = fs.createWriteStream('file.txt');
var r = require('rethinkdbdash')();
r.table('users').toStream()
.on('error', console.log)
.pipe(file)
.on('error', console.log)
.on('end', function() {
r.getPool().drain();
});
Note: The stream will emit an error if you provide it with a single value (streams, arrays
and grouped data work fine).
Note: null
values are currently dropped from streams.
Writable and Transform streams
You can create a Writable
or Transform streams by
calling toStream([connection, ]{writable: true})
or
toStream([connection, ]{transform: true})
on a table.
This makes a convenient way to dump a file your database.
var file = fs.createReadStream('users.json')
var table = r.table('users').toStream({writable: true});
file.pipe(transformer)
.pipe(table)
.on('finish', function() {
console.log('Done');
r.getPool().drain();
});
Optional run
with yield
The then
and catch
methods are implemented on a Term
- returned by any methods
like filter
, update
etc. They are shortcut for this.run().then(callback)
and
this.run().catch(callback)
.
This means that you can yield
any query without calling run.
var bluebird = require('bluebird');
var r = require('rethinkdbdash')();
bluebird.coroutine(function*() {
try {
var result = yield r.table('users').get('orphee@gmail.com').update({name: 'Michel'});
assert.equal(result.errors, 0);
} catch(err) {
console.log(err);
}
});
Note: You have to start Node >= 0.11 with the --harmony
flag.
Global default values
You can set the maximum nesting level and maximum array length on all your queries with:
r.setNestingLevel(<number>)
r.setArrayLimit(<number>)
Undefined values
Rethinkdbdash will ignore the keys/values where the value is undefined
instead
of throwing an error like the official driver.
Better errors
Backtraces
If your query fails, the driver will return an error with a backtrace; your query
will be printed and the broken part will be highlighted.
Backtraces in rethinkdbdash are tested and properly formatted. Typically, long backtraces
are split on multiple lines and if the driver cannot serialize the query,
it will provide a better location of the error.
Arity errors
The server may return confusing error messages when the wrong number
of arguments is provided (See rethinkdb/rethinkdb#2463 to track progress).
Rethinkdbdash tries to make up for it by catching errors before sending
the query to the server if possible.
Performance
The tree representation of the query is built step by step and stored which avoid
recomputing it if the query is re-run.
The code was partially optimized for v8, and is written in pure JavaScript which avoids
errors like issue #2839
Run tests
Update test/config.js
if your RethinkDB instance doesn't run on the default parameters.
Make sure you run a version of Node that supports generators and run:
npm test
Tests are also being run on wercker:
FAQ
-
Why rethinkdbdash?
Rethinkdbdash was built as an experiment for promises and a connection pool. Its
purpose was to test new features and improve the official driver. Today,
rethinkdbdash still tries to make the developer experience as pleasant as possible -
like with the recent support for Node.js streams.
Some features like promises have been back ported to the official driver, some like
the connection pool and streams are on their way.
-
Is it stable?
Yes. Rethinkdbdash is used by quite many people. The driver is also used by thinky
,
and has been and is still being tested in the wild.
-
Does it work with io.js?
All the tests pass with io.js so yes.
-
Is rethinkdbdash going to become the JavaScript official driver?
Not (yet?), maybe :)
Completely replacing the driver requires some work:
- Integrate the driver in RethinkDB suite test.
- Support HTTP connections.
- Rollback some default like the coercion of cursors to arrays.
-
Can I contribute?
Feel free to send a pull request. If you want to implement a new feature, please open
an issue first, especially if it's a non backward compatible one.