Curriculum
Cassandra collections are data types that allow you to store multiple values within a single column in a Cassandra database. Collections in Cassandra include lists, sets, and maps. They are useful for handling complex data types, such as arrays or dictionaries, in a distributed database environment.
In this tutorial, we will explore the different types of collections available in Cassandra and how they can be used in your data modeling.
To use collections in Cassandra, you must first create a table with a column of the appropriate collection type. For example, to create a table with a list column, you can use the following CQL statement:
CREATE TABLE my_table ( id INT PRIMARY KEY, my_list LIST<TEXT> );
Once you have created the table, you can insert data into it using the appropriate collection functions. For example, to insert data into a list column, you can use the append
function:
INSERT INTO my_table (id, my_list) VALUES (1, ['apple', 'orange', 'banana']);
To retrieve data from a collection column, you can use the appropriate collection functions. For example, to retrieve all the elements in a list column, you can use the SELECT
statement:
SELECT my_list FROM my_table WHERE id=1;
To update data in a collection column, you can use the appropriate collection functions. For example, to append a new element to a list column, you can use the append
function:
UPDATE my_table SET my_list = my_list + ['grape'] WHERE id=1;
To delete data from a collection column, you can use the appropriate collection functions. For example, to remove an element from a list column, you can use the remove
function:
DELETE my_list[2] FROM my_table WHERE id=1;
Cassandra collections are a powerful feature that allows you to store complex data types within a single column in a Cassandra database. By understanding the different types of collections available and their limitations, you can design a data model that works best for your specific use case.