Cassandra

In Greek mythology, Cassandra was the daughter of King Priam and Queen Hecuba, of Illiad fame. Apollo granted her the power of prophecy in order to seduce her, and cursed her to never be believed when she rejected him.

It's also software by Apache designed to handle large amounts of data in a scalable way. Intended for cloud and cluster solutions/applications. Used by companies like Netflix.

CQL

The Cassandra Query Language (CQL) is a query language specific to Cassandra that looks a lot like SQL.

Using

Command Line Client

Cassandra can be used from the command line via the cqlsh tool, which provides a Cassandra shell from which CQL commands can be executed.

Like MySQL, you start up the command line program, which starts a client that tries to connect to a server instance. To connect to a local instance, specify localhost as the host:

$ bin/cqlsh localhost
Connected to Test Cluster at localhost:9042.
[cqlsh 5.0.1 | Cassandra 3.8 | CQL spec 3.4.2 | Native protocol v4]
Use HELP for help.
cqlsh>

You can specify various command line options (e.g., username/password, script file, startup file, etc.)

A simple hello world query in CQL:

cqlsh> SELECT cluster_name, listen_address FROM system.local;

 cluster_name | listen_address
--------------+----------------
 Test Cluster |      127.0.0.1

(1 rows)

Full cqlsh documentation: https://cassandra.apache.org/doc/latest/tools/cqlsh.html#cqlsh

Using Other Languages

You can interface with Cassandra from a number of different languages (Java, Python, Node, Scala, Go, Rust, etc.). Full list of client drivers: https://cassandra.apache.org/doc/latest/getting_started/drivers.html

Using on Google Cloud

Google Cloud offers several pre-configured virtual machine instances that run Cassandra, including one created by Google, and one created by Bitnami. See Google Cloud/Cassandra