Cassandra golang client

Happy searchOps

(λx.x)eranga

Published in

Effectz.AI

2 min readNov 1, 2019

Gocql

gocql is the cassandra driver for the go programming language. It support for all common cassandra data types including sets, lists, maps, udt etc. Custom types can implement a Marshaler and Unmarshaler interface. It built-in support for UUIDs, cluster management, TLS/SSL communication, automatic query preparation, etc.

On my previous post I have discussed about building cassandra scala client application. In this post I will discuss about building cassandra golang client application with using gocql package. All source codes which relates to this post available on gitlab. Please clone the repository and continue the post.

Run Cassandra

I have run Cassandra with Elassandra docker image. Elassandra built by combining Elasticseach with Cassandra. It comes Elasticsearch as a Cassandra plugin. Basically it has Cassandra API as well as Elasticsearch API. When data save on Cassandra it will automatically index on Elasticsearch. Read more about elassandra from here. Following is the docker-compose.yml to run the elassandra.

Now I can run the Elassandra with following commands. It will start Cassandra on my local machine. I can access the Cassandra via Cqlsh inside the Elassandra docker container.

Cassandra schemas

In cassandra I have a keyspace named mystiko and table a named documents. documents table contains a UDT SET named signatures. Following are the schemas.

Dependencies

I have used gocql (golang cassandra client driver) and mapstructure (golang library for decoding generic map values to structures and vice versa) libraries. Following is the way to install these libraries

Cassandra config

The cassandra configurations defined in config.go file. It contains host, port, keyspace etc informations. There configurations can be loaded via environment variables(12factor apps)

Struct types

I have defined the document and signatures in cassandra schema as struct types. These struct objects used when creating/querying the documents on cassandra.

Cassandra session

In order to interact with cassandra, I need to create a gocql.Session with cassandra cluster configurations. gocql.Session is safe for concurrent use by multiple goroutines and a typical usage scenario is to have one global session object to interact with the whole Cassandra cluster(no need to create connection pool).

Cassandra queries

Following are the various query function that I have defined to create, update, search documents.

Test queries

Following is the main application(main.go) which executes these queries. It first initialize the session, then execute queries and finally close the session.