Question

Can anyone provide a clear example of how to remove a supercolumn in Java using thrift?

Edit: Found a solution, this allows me to delete any number of supercolumns that I want in one batch mutate.

    List<Mutation> mutations = new ArrayList<Mutation>();
    Map<String, List<Mutation>> keyMutations = new HashMap<String, List<Mutation>>();
    Map<ByteBuffer, Map<String, List<Mutation>>> mutationsMap = new HashMap<ByteBuffer, Map<String, List<Mutation>>>();
    try {
        tr.open();
        client.set_keyspace("my_keyspace");

        Deletion deletion = new Deletion();
        SlicePredicate slicePredicate = new SlicePredicate();

        List<ByteBuffer> columns = new ArrayList<ByteBuffer>();

        // Add as many supercolumns as you want here 
        columns.add(toByteBuffer("supercolumn_name"));

        slicePredicate.setColumn_names(columns);
        deletion.setPredicate(slicePredicate);

        // timestamp in microseconds        
        deletion.setTimestamp(System.currentTimeMillis() * 1000);

        Mutation m = new Mutation();
        m.setDeletion(deletion);

        mutations.add(m);

        keyMutations.put("column_family_name", mutations);

        mutationsMap.put(toByteBuffer("row_id_in_column_family"), keyMutations);
        client.batch_mutate(mutationsMap, ConsistencyLevel.ONE);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
         tr.flush();
         tr.close();
    }

Answer 1

Found a solution, this allows me to delete any number of supercolumns that I want in one batch mutate.

List<Mutation> mutations = new ArrayList<Mutation>();
Map<String, List<Mutation>> keyMutations = new HashMap<String, List<Mutation>>();
Map<ByteBuffer, Map<String, List<Mutation>>> mutationsMap = new HashMap<ByteBuffer, Map<String, List<Mutation>>>();
try {
    tr.open();
    client.set_keyspace("my_keyspace");

    Deletion deletion = new Deletion();
    SlicePredicate slicePredicate = new SlicePredicate();

    List<ByteBuffer> columns = new ArrayList<ByteBuffer>();

    // Add as many supercolumns as you want here 
    columns.add(toByteBuffer("supercolumn_name"));

    slicePredicate.setColumn_names(columns);
    deletion.setPredicate(slicePredicate);

    // timestamp in microseconds        
    deletion.setTimestamp(System.currentTimeMillis() * 1000);

    Mutation m = new Mutation();
    m.setDeletion(deletion);

    mutations.add(m);

    keyMutations.put("column_family_name", mutations);

    mutationsMap.put(toByteBuffer("row_id_in_column_family"), keyMutations);
    client.batch_mutate(mutationsMap, ConsistencyLevel.ONE);
} catch (Exception e) {
    e.printStackTrace();
} finally {
     tr.flush();
     tr.close();
}