Cassandra

A wrapper for nodejs-cassandra library, providing promises and a set of convenience methods.

NOTE: this library is not very customizable nor will it be, its intent is to serve as a standard for my personal projects. There are only few tests because its use is extensively tested in component tests.

Connect

Run connect(...) before executing any statements.

cassandra.connect({
  contactPoints: ['localhost'],
});

Available options are all cassandra-driver ClientOptions.

createKeyspace(...)

cassandra.createKeyspace('test', 'NetworkTopologyStrategy')
  .then(() => console.log('Keyspace "test" created'));

A USE {keyspace} statement is executed afterwards.

dropKeyspace(...)

cassandra.dropKeyspace('test')
  .then(() => console.log('Keyspace "test" created'));

execute(...)

cassandra.execute(`SELECT * FROM users WHERE id=?`, ['a813g1e'], { prepare: true })
  .then((result) => console.log('Result', result));

preparedInsert(...)

Creates a prepared INSERT statement based on an object by mapping its keys to fields.

You can use this for update statements as well because Cassandra's INSERT and UPDATE are almost identical with the exception of counter columns.

const query = cassandra.preparedInsert('users', {
  id: 'a7509gd',
  first_name: 'John',
  last_name: 'Doe',
}, { ttl: 3600 * 24 * 31, notExists: true });

/*
{
  query: 'INSERT INTO users (first_name, id, last_name) VALUES (?, ?, ?) IF NOT EXISTS USING TTL 2678400',
  params: [ 'John', 'a7509gd', 'Doe' ]
}
*/
console.log(query);

Option | Default | Description ----------|---------|------------------ notExists | false | Adds IF NOT EXISTS clause to prepared query ttl | null | umber of seconds after which record is deleted. Set null to never expire data.

batch(..)

Batch method is a minimal wrapper around nodejs-cassandra's batch statement. It returns a promise with the result of the BATCH operation.

const queries = [{
  query: 'UPDATE users SET name=? WHERE id=?',
  params: ['John', 'ae835x'],
}, {
  query: 'INSERT INTO users (id, name, created) VALUES (?, ?, ?)',
  params: ['1g0fee', 'hendrix', new Date()],
}];

cassandra.batch(queries, { prepare: true }).catch(err => {
  assert.ifError(err);
  console.log('Data updated on cluster');
});

The most common options are listed below, you can find more here.

Option | Default | Description ----------|---------|----------------------------- prepare | false | Queries are prepared statements. logged | true | Whether batch should be written to the batchlog.

Be aware batch in Cassandra is not a performance improvement in most situations, instead it provides support for atomic transactions (either all operations succeed or none).

The one exception a batch does improve performance is when a set of writes are written to the same partition.

Logging

import * as cassandra from '@nielskrijger/cassandra';

cassandra.on('log', (level, message, object) => {
  console.log(`Log event: ${level}, ${message}, ${object}`);
});

A debug log event is emitted when executing a statement or a batch of statements. An info log event is emitted when connection was established.

Errors must be handled by the client as part of the Promise chain, no log events are emitted.