CODEWITHSUNDEEP
cassandracqlcassandra-3.0
sparkless
sparkless

Reputation: 305

Primary Key without Clustering Key in Cassandra

I want to use two fields as primary key (without clustering key).

PRIMARY KEY ((a, b)) => is that means a + b is the primary key, right? Or is it just partition key?

I'm confused

Upvotes: 1

Views: 1142

Answers (2)

Erick Ramirez
Erick Ramirez

Reputation: 16393

To add to Aaron's response, the brackets (( and )) combine the 2 columns into one partition key. This means that you need to provide both columns in your filter in order to query the table:

SELECT ... FROM ... WHERE a = ? AND b = ?

Neither of these queries are valid because they only filter on 1 of the 2:

SELECT ... FROM ... WHERE a = ?

SELECT ... FROM ... WHERE b = ?

For what it's worth, I've explained the terms "composite partition key" and "compound primary key" with some real examples to illustrate the differences in this post -- https://community.datastax.com/questions/6171/. Cheers!

Upvotes: 3

Aaron
Aaron

Reputation: 57808

A primary key definition of:

PRIMARY KEY ((a, b))

...sets both a and b as a composite partition key. In this scenario, there is no clustering key.

This definition:

PRIMARY KEY (a, b)

...uses a as the partition key and b as the clustering key.

For more info, I recommend Carlo's famous answer to this question:

Difference between partition key, composite key and clustering key in Cassandra?

Upvotes: 4

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