Querying the count of rows from a Cassandra table in a Java application could be a bit tricky, because you can’t use the com.datastax.driver.mapping.Result<T> return type with the returned Long value returned by the count.
If you are trying to do that you could get an exception containing something like this:
@Table annotation was not found on class java.lang.Long
Yes the Result<T> type can only be used if you have a @Table annotated class. But this solution is not for returning counts.
To return the count, you have to use com.datastax.driver.core.ResultSet as your return type. You could have a query like this in your @Accessor interface.
@Accessor
public interface MyAccessor {
@Query("SELECT COUNT(*) FROM tableName")
ResultSet countAll();
}
Then, in your DAO, where you use this accessor, you can do the following to get the long value:
long count = this.myAccessor.countAll().one().getLong(0);