Using a counter

A counter is a special column for storing a number that is changed in increments.

To load data into a counter column, or to increase or decrease the value of the counter, use the UPDATE command. DataStax Distribution of Apache Cassandra rejects USING TIMESTAMP or USING TTL in the command to update a counter column.

Procedure

  • Create a table for the counter column.
    USE cycling;
    CREATE TABLE popular_count (
      id UUID PRIMARY KEY,
      popularity counter
      );
  • Loading data into a counter column is different than other tables. The data is updated rather than inserted.
    UPDATE cycling.popular_count
     SET popularity = popularity + 1
     WHERE id = 6ab09bec-e68e-48d9-a5f8-97e6fb4c9b47;
  • Take a look at the counter value and note that popularity has a value of 1.
    SELECT * FROM cycling.popular_count;
  • Additional increments or decrements will change the value of the counter column.