Counters

Counter Columns

Counters were added in the 0.8x branch of Cassandra. clj-hector provides basic support currently.

Create a Column Family

Firstly, you'll need to make sure you've created a column family that has the default validator set to CounterColumnType. Using the clj-hector.ddl/add-keyspace function you can create a compatible column family as follows:

(ddl/add-keyspace *cluster* {:name "Keyspace"
                             :strategy :local
                             :replication 1
                             :column-families [{:name cf
                                                :validator :counter}]})

Updating Counters

Once you've defined your keyspace (and column family), you can store counter values.

For example, to store in the column family above, use the clj-hector.core/put-counter function:

(put-counter ks cf pk {"first-counter" 1 "other-counter" 2})

And the value can be queried with

(get-counter-columns ks cf pk ["name" "other"] {:n-serializer :string :v-serializer :long})