UUID Cassandra

Question

I am new to Kassandra. I am trying to insert some values ​​in columnfamily. The definition of columnfamily in the configuration file is as follows.

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

When I try to insert values, I always get a "InvalidRequestException (why: UUID must be exactly 16 bytes)".

I use batch_mutate () to insert a column.

How to insert values ​​into a column family.

Answer 1

Below is a snippet of code (from Nick Berardi Coder Magazine )

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);
    }

Answer 2

"We have an API for this" :-)

https://github.com/rantav/hector/blob/master/core/src/main/java/me/prettyprint/cassandra/utils/TimeUUIDUtils.java

UIID 1 . . .

MIT, , , , .

Answer 3

, "" . GUID columnfamilies.

Mutation foobar = new Mutation()
{
     Column_or_supercolumn = new ColumnOrSuperColumn() 
       { Super_column = new SuperColumn() 
         { Name = GuidGenerator.GenerateTimeBasedGuid(DateTime.Now).ToByteArray(), 
               Columns = listOfSomeColumns
          } 
        }
};

List<Column> foobarlist = new List<Column>();
listOfChannelIds.Add(new Column() { Name = utf8Encoding.GetBytes("somename"), Value = utf8Encoding.GetBytes(somestring), Timestamp = timeStamp });

GUID SupercolumnName, columnName .

Answer 4

Cassandra , UUID RFC 4122, , ( UUID).