在.net中使用aquiles访问Cassandra(三)

之前我们实现了如何修改数据，还需要相应的删除动作。删除方式会有几种情况，以下分别一一介绍。

 

1.批量删除，适应于多行多列的情况。

public void Remove(string columnFamily, IList<RowMutation> rowMutations)
{
    if (string.IsNullOrWhiteSpace(columnFamily)) throw new ArgumentNullException("columnFamily");

    Dictionary<byte[], Dictionary<string, List<Apache.Cassandra.Mutation>>> mutation_map = new Dictionary<byte[], Dictionary<string, List<Apache.Cassandra.Mutation>>>();

    foreach (var rowMutation in rowMutations)
    {
        byte[] key = ByteEncoderHelper.UTF8Encoder.ToByteArray(rowMutation.Key);

        Dictionary<string, List<Apache.Cassandra.Mutation>> cfMutation = new Dictionary<string, List<Apache.Cassandra.Mutation>>();
        List<Apache.Cassandra.Mutation> mutationList = new List<Apache.Cassandra.Mutation>();

        Apache.Cassandra.Mutation mutation = new Apache.Cassandra.Mutation();
        mutation.Deletion = new Deletion();
        if (rowMutation.Mutations != null && rowMutation.Mutations.Count > 0)
        {
            mutation.Deletion.Predicate = new SlicePredicate()
            {
                Column_names = rowMutation.Mutations.Select(
                m => ByteEncoderHelper.UTF8Encoder.ToByteArray(m.ColumnName)).ToList()
            };
        }
        mutation.Deletion.Timestamp = DateTime.Now.ToUnixTimestamp();
        mutationList.Add(mutation);

        cfMutation.Add(columnFamily, mutationList);
        mutation_map.Add(key, cfMutation);
    }

    if (mutation_map.Count == 0) return;
    _cluster.Execute(new ExecutionBlock(delegate(Apache.Cassandra.Cassandra.Client client)
    {
        client.batch_mutate(mutation_map, _consistencyLevel);
        return null;
    }), _keyspaceName);

}

2.删除指定的行。

public void Remove(string columnFamily, string rowKey)
{
    if (string.IsNullOrWhiteSpace(columnFamily)) throw new ArgumentNullException("columnFamily");

    byte[] key = ByteEncoderHelper.UTF8Encoder.ToByteArray(rowKey);

    ColumnPath columnPath = new ColumnPath()
      {
          Column_family = columnFamily,
      };

    _cluster.Execute(new ExecutionBlock(delegate(Apache.Cassandra.Cassandra.Client client)
      {
          client.remove(key, columnPath, DateTime.Now.ToUnixTimestamp(), _consistencyLevel);
          return null;
      }), _keyspaceName);
}

3.删除指定行指定列。

public void Remove(string columnFamily, string rowKey, string columnName)
{
    if (string.IsNullOrWhiteSpace(columnFamily)) throw new ArgumentNullException("columnFamily");

    byte[] key = ByteEncoderHelper.UTF8Encoder.ToByteArray(rowKey);

    ColumnPath columnPath = new ColumnPath()
    {
        Column_family = columnFamily,
        Column = ByteEncoderHelper.UTF8Encoder.ToByteArray(columnName)
    };

    _cluster.Execute(new ExecutionBlock(delegate(Apache.Cassandra.Cassandra.Client client)
    {
        client.remove(key, columnPath, DateTime.Now.ToUnixTimestamp(), _consistencyLevel);
        return null;
    }), _keyspaceName);
}

4.删除多行，使用批量删除方法完成。

public void Remove(string columnFamily, IList<string> rowKeys)
{
    IList<RowMutation> batchMutations = new List<RowMutation>();
    foreach (string rowKey in rowKeys)
    {
        batchMutations.Add(new RowMutation(rowKey));
    }
    Remove(columnFamily, batchMutations);
}

5.删除一行多列，同样调用指量删除方法完成。

public void Remove(string columnFamily, string rowKey, IList<string> columnNames)
{
    IList<RowMutation> rowMutations = new List<RowMutation>();

    RowMutation rowMutation = new RowMutation();
    rowMutation.Key = rowKey;

    rowMutation.Mutations = new List<CellMutation>();
    foreach (string columnName in columnNames)
    {
        rowMutation.Mutations.Add(new CellMutation(columnName));
    }
    rowMutations.Add(rowMutation);

    Remove(columnFamily, rowMutations);
}