DataStax Node.js Driver for Apache Cassandra

Node.js driver for Apache Cassandra. This driver works exclusively with the Cassandra Query Language version 3 (CQL3) and Cassandra's native protocol.

Installation

$ npm install cassandra-driver

Features

Node discovery
Configurable load balancing
Transparent failover
Tunability
Paging
Client-to-node SSL support
Row streaming
Prepared statements and query batches

Documentation

Getting Help

You can use the project mailing list or create a ticket on the Jira issue tracker.

Basic usage

var cassandra = require('cassandra-driver');
var client = new cassandra.Client({contactPoints: ['host1', 'h2'], keyspace: 'ks1'});
var query = 'SELECT email, last_name FROM user_profiles WHERE key=?';
client.execute(query, ['guy'], function(err, result) {
  assert.ifError(err);
  console.log('got user profile with email ' + result.rows[0].email);
});

Prepare your queries

Use prepared statements to obtain best performance. The driver will prepare the query once on each host and execute the statement with the bound parameters.

//When using parameter markers ? the prepared query will be reused
var query = 'UPDATE user_profiles SET birth=? WHERE key=?'; 
var params = [new Date(1942, 10, 1), 'jimi-hendrix'];
//Set the prepare flag in the query options
client.execute(query, params, {prepare: true}, function(err) {
  assert.ifError(err);
  console.log('Row updated on the cluster');
});

Avoid buffering

When using #eachRow() and #stream() methods, the driver parses each row as soon as it is received, yielding rows without buffering them.

//Reducing a large result
client.eachRow('SELECT time, val FROM temperature WHERE station_id=', ['abc'],
  function(n, row) {
    //the callback will be invoked per each row as soon as they are received
    minTemperature = Math.min(row.val, minTemperature);
  },
  function (err) {
    assert.ifError(err);
  }
);

The #stream() method works in the same way but instead of callback it returns a Readable Streams2 object in objectMode that emits instances of Row. It can be piped downstream and provides automatic pause/resume logic (it buffers when not read).

Paging

All driver methods use a default fetchSize of 5000 rows, retrieving only first page of results up to a maximum of 5000 rows to shield an application against accidentally large result sets. To retrieve the following records you can use the autoPage flag in the query options of #eachRow() and #stream() methods.

//Imagine a column family with millions of rows
var query = 'SELECT * FROM largetable';
client.eachRow(query, [], {autoPage: true}, function (n, row) {
  //This function will be called per each of the rows in all the table
}, endCallback);

Batch multiple statements

You can execute multiple statements in a batch to update/insert several rows atomically even in different column families.

var queries = [
  {
    query: 'UPDATE user_profiles SET email=? WHERE key=?',
    params: [emailAddress, 'hendrix']
  },
  {
    query: 'INSERT INTO user_track (key, text, date) VALUES (?, ?, ?)',
    params: ['hendrix', 'Changed email', new Date()]
  }
];
var queryOptions = { consistency: cassandra.types.consistencies.quorum };
client.batch(queries, queryOptions, function(err) {
  assert.ifError(err);
  console.log('Data updated on cluster');
});

Data types

There are few data types defined in the ECMAScript standard, this usually represents a problem when you are trying to deal with data types that come from other systems in javascript.

You should read the documentation on CQL data types and ECMAScript types for more information.

Logging

Instances of Client() are EventEmitter and emit log events:

client.on('log', function(level, className, message, furtherInfo) {
  console.log('log event: %s -- %s', level, message);
});

The level being passed to the listener can be verbose, info, warning or error.

Credits

This driver is based on the original work of Jorge Bay on node-cassandra-cql and adds a series of advanced features that are common across all other DataStax drivers for Apache Cassandra.

The development effort to provide an up to date, high performance, fully featured Node.js Driver for Apache Cassandra will continue on this project, while node-cassandra-cql will be discontinued.

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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