Question

I am new to Cassandra. I am trying to insert some values to the columnfamily. The definition of columnfamily in the config file is as follows.

<ColumnFamily Name="CommandQueue"
                    ColumnType="Super"
                    CompareWith="TimeUUIDType"
                    CompareSubcolumnsWith="UTF8Type"/>

When ever I try to insert values to I always get “InvalidRequestException(why: UUIDs must be exactly 16 bytes)”.

I am using batch_mutate() to insert column.

How can I insert values to the column family.

Answer 1

Below is a code snippet (from Nick Berardi’s Coder Journal)

public static Guid GenerateTimeBasedGuid(DateTime dateTime)
    {
        long ticks = dateTime.Ticks - GregorianCalendarStart.Ticks;

        byte[] guid = new byte[ByteArraySize];
        byte[] clockSequenceBytes = BitConverter.GetBytes(Convert.ToInt16(Environment.TickCount
            % Int16.MaxValue));
        byte[] timestamp = BitConverter.GetBytes(ticks);

        // copy node
        Array.Copy(Node, 0, guid, NodeByte, Node.Length);

        // copy clock sequence
        Array.Copy(clockSequenceBytes, 0, guid, GuidClockSequenceByte,clockSequenceBytes.Length);

        // copy timestamp
        Array.Copy(timestamp, 0, guid, 0, timestamp.Length);

        // set the variant
        guid[VariantByte] &= (byte)VariantByteMask;
        guid[VariantByte] |= (byte)VariantByteShift;

        // set the version
        guid[VersionByte] &= (byte)VersionByteMask;
        guid[VersionByte] |= (byte)((int)GuidVersion.TimeBased << VersionByteShift);

        return new Guid(guid);
    }