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Primary keys in YugabyteDB YCQL

docs/content/v2.20/explore/ycql-language/indexes-constraints/primary-key-ycql.md

2026.1.0.0-b294.2 KB
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The Primary Key constraint is a means to uniquely identify a specific row in a table via one or more columns. In YCQL, it should be defined either under the column_constraint or the table_constraint, but not under both:

  • column_constraint: Columns can be either STATIC or declared as the PRIMARY KEY. Declaring a column as STATIC results in the same value being shared for all those rows that belong to the same partition (rows with the partition key). Declaring a column as a PRIMARY KEY makes that individual column its sole component.

  • table_constraint: PRIMARY KEY defined as the table_constraint takes columns to form one or more partition keys and zero or more clustering keys. Syntactically, the order is to have the partition_key_column_list first, followed by the clustering_key_column_list.

Refer to the Grammar section for CREATE TABLE in YCQL. The PRIMARY KEY section includes details about the partition key, clustering key, and STATIC COLUMNS.

Examples

{{% explore-setup-single %}}

Column constraint

  1. Create a users table with user_id as the primary key.

    cql
    CREATE TABLE users(user_id INT PRIMARY KEY, full_name TEXT);

  2. Insert two rows into the table and check the entries.

    cql
    INSERT INTO users(user_id , full_name) VALUES (1, 'John');
INSERT INTO users(user_id , full_name) VALUES (1, 'Rose');
SELECT * FROM users;
    output
     user_id | full_name
---------+-----------
       1 |       Rose

The second entry with Rose as the full_name overrides the first entry because the user_id is the same.

Table constraint

  1. Create a devices table with supplier_id and device_id as the partitioning columns and model year as the clustering column.

    cql
    CREATE TABLE devices(supplier_id INT,
                    device_id INT,
                    model_year INT,
                    device_name TEXT,
                    PRIMARY KEY((supplier_id, device_id), model_year));

  2. Insert three rows into the table and view the contents.

    cql
    INSERT INTO devices(supplier_id, device_id, device_name, model_year) VALUES (1, 101, 'iPhone', 2013);
INSERT INTO devices(supplier_id, device_id, device_name, model_year) VALUES (1, 102, 'Pixel', 2011);
INSERT INTO devices(supplier_id, device_id, device_name, model_year) VALUES (1, 102, 'Samsung S3', 2001);
SELECT * FROM devices;
    output
     supplier_id | device_id | model_year | device_name
-------------+-----------+------------+-------------
           1 |       101 |       2013 |      iPhone
           1 |       102 |       2001 |     Samsung
           1 |       102 |       2011 |       Pixel

(3 rows)

  3. Insert another entry with supplier_id, device_id, and model_year as 1, 102, and 2011 respectively.

    cql
    INSERT INTO devices(supplier_id, device_id, device_name, model_year) VALUES (1, 102, 'MotoRazr', 2011);
SELECT * FROM devices;
    output
     supplier_id | device_id | model_year | device_name
-------------+-----------+------------+-------------
           1 |       101 |       2013 |      iPhone
           1 |       102 |       2001 |     Samsung
           1 |       102 |       2011 |    MotoRazr

The row with device_name Pixel is replaced with MotoRazr.

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