Question

I am new to cassandra and find it a bit difficult to understand in creating a simple keyspace with some structure that I am thinking of. I created a keyspace called “acquisition” using the cassandra CLI.

Using Cassandra-CLI how can I create the following for the “acquisition” keyspace –

TagNo // This is the super column
{
  ID // This is the column family
   {
     // here we shall have lots of entries. (Rows)
     user1: {rate, distance, capacity}
     user2: {rate, distance, capacity}
    }    
}

Rate distance and capacity can be stored as either strings or doubles. But does not really matter at the moment.

I am not sure how on to do this using the CLI. So please help

Answer 1

• create keyspace.

  create keyspace acquisition with placement_strategy =
  ‘org.apache.cassandra.locator.SimpleStrategy’ and strategy_options =
  {replication_factor:1};

• create super column family.

  create column family TagNo with column_type = 'Super' and comparator = 'UTF8Type' and subcomparator = 'UTF8Type' and default_validation_class = 'UTF8Type' and column_metadata = [{ column_name : rate, validation_class : AsciiType}, { column_name : 'distance', validation_class : AsciiType}, {column_name : 'capacity', validation_class : AsciiType}];
  

• set a few example values to the TagNo super column family.

  [default@acquisition] set TagNo[utf8('ID')]['user1']['rate'] = '10';
  Value inserted.
  Elapsed time: 2 msec(s).
  [default@acquisition] set TagNo[utf8('ID')]['user1']['distance'] = '100'; 
  Value inserted.
  Elapsed time: 2 msec(s).
  [default@acquisition] set TagNo[utf8('ID')]['user1']['capacity'] = '50';
  Value inserted.
  Elapsed time: 2 msec(s).
  [default@acquisition] set TagNo[utf8('ID')]['user2']['capacity'] = '50';
  Value inserted.
  Elapsed time: 2 msec(s).
  [default@acquisition] set TagNo[utf8('ID')]['user2']['rate'] = '20';
  Value inserted.
  Elapsed time: 1 msec(s).
  [default@acquisition] set TagNo[utf8('ID')]['user2']['distance'] = '100'; 
  Value inserted.
  Elapsed time: 2 msec(s).
  

• show values..

  [default@acquisition] get TagNo[utf8('ID')];
  => (super_column=user1,
       (column=capacity, value=50, timestamp=1331605812776000)
       (column=distance, value=100, timestamp=1331605805912000)
       (column=rate, value=10, timestamp=1331605780216000))
  => (super_column=user2,
       (column=capacity, value=50, timestamp=1331605816568000)
       (column=distance, value=100, timestamp=1331605846008000)
       (column=rate, value=20, timestamp=1331605821608000))
  Returned 2 results.
  Elapsed time: 3 msec(s).