Ok, I made the changes and tried again.  Here is the before modifying my method using a simple get, confirmed the same output in the cli:

DEBUG [pool-1-thread-2] 2011-04-18 09:37:23,910 CassandraServer.java (line 279) get
DEBUG [pool-1-thread-2] 2011-04-18 09:37:23,911 StorageProxy.java (line 322) Command/ConsistencyLevel is SliceByNamesReadCommand(table='DocStore', key=64316337663662392d313432352d346661622d623037342d353537346335346361653038, columnParent='QueryPath(columnFamilyName='Tran
slationsByTarget', superColumnName='java.nio.HeapByteBuffer[pos=95 lim=211 cap=244]', columnName='null')', columns=[7c2f5d5b-b370-42e1-a6a2-77fc721440fe,])/ALL
DEBUG [pool-1-thread-2] 2011-04-18 09:37:23,911 ReadCallback.java (line 84) Blockfor/repair is 1/true; setting up requests to localhost/127.0.0.1
DEBUG [pool-1-thread-2] 2011-04-18 09:37:23,911 StorageProxy.java (line 345) reading data locally
DEBUG [ReadStage:4] 2011-04-18 09:37:23,911 StorageProxy.java (line 450) LocalReadRunnable reading SliceByNamesReadCommand(table='DocStore', key=64316337663662392d313432352d346661622d623037342d353537346335346361653038, columnParent='QueryPath(columnFamilyName='Translatio
nsByTarget', superColumnName='java.nio.HeapByteBuffer[pos=95 lim=211 cap=244]', columnName='null')', columns=[7c2f5d5b-b370-42e1-a6a2-77fc721440fe,])
DEBUG [pool-1-thread-2] 2011-04-18 09:37:23,912 StorageProxy.java (line 395) Read: 1 ms.
ERROR [pool-1-thread-2] 2011-04-18 09:37:23,912 Cassandra.java (line 2665) Internal error processing get
java.lang.AssertionError
        at org.apache.cassandra.thrift.CassandraServer.get(CassandraServer.java:300)
        at org.apache.cassandra.thrift.Cassandra$Processor$get.process(Cassandra.java:2655)
        at org.apache.cassandra.thrift.Cassandra$Processor.process(Cassandra.java:2555)
        at org.apache.cassandra.thrift.CustomTThreadPoolServer$WorkerProcess.run(CustomTThreadPoolServer.java:206)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
        at java.lang.Thread.run(Thread.java:636)

And here is the after...it succeeds here but still gives me multiple subcolumns in the response.  Same behavior, it seems, I'm just sidestepping the original AssertionError:

DEBUG [pool-1-thread-6] 2011-04-18 09:50:26,617 CassandraServer.java (line 232) get_slice
DEBUG [pool-1-thread-6] 2011-04-18 09:50:26,617 StorageProxy.java (line 322) Command/ConsistencyLevel is SliceByNamesReadCommand(table='DocStore', key=64316337663662392d313432352d346661622d623037342d353537346335346361653038, columnParent='QueryPath(columnFamilyName='TranslationsByTarget', superColumnName='java.nio.HeapByteBuffer[pos=101 lim=217 cap=259]', columnName='null')', columns=[7c2f5d5b-b370-42e1-a6a2-77fc721440fe,])/ALL
DEBUG [pool-1-thread-6] 2011-04-18 09:50:26,617 ReadCallback.java (line 84) Blockfor/repair is 1/true; setting up requests to localhost/127.0.0.1
DEBUG [pool-1-thread-6] 2011-04-18 09:50:26,617 StorageProxy.java (line 345) reading data locally
DEBUG [ReadStage:3] 2011-04-18 09:50:26,618 StorageProxy.java (line 450) LocalReadRunnable reading SliceByNamesReadCommand(table='DocStore', key=64316337663662392d313432352d346661622d623037342d353537346335346361653038, columnParent='QueryPath(columnFamilyName='TranslationsByTarget', superColumnName='java.nio.HeapByteBuffer[pos=101 lim=217 cap=259]', columnName='null')', columns=[7c2f5d5b-b370-42e1-a6a2-77fc721440fe,])
DEBUG [pool-1-thread-6] 2011-04-18 09:50:26,618 StorageProxy.java (line 395) Read: 0 ms.

My comparators are relatively simple.  Basically I have a schema that required heterogenous columns, but I needed to be able to deserialize them in unique ways.  So there is always a type byte that precedes the bytes of the data.  The supercolumn in this case is a general data type, which happens to represent a serializable object:

  public void validate(ByteBuffer bytes)
    throws MarshalException
  {
    if(bytes.remaining() == 0)
      return;

    validateDataType(bytes.get(bytes.position()));
    return;
  }

  public int compare(ByteBuffer bytes1, ByteBuffer bytes2)
  {
    if (bytes1.remaining() == 0)
      return bytes2.remaining() == 0 ? 0 : -1;
    else if (bytes2.remaining() == 0)
      return 1;
    else
    {
      // compare type bytes                                                                                                                                                                                                                                                   
      byte T1 = bytes1.get(bytes1.position());
      byte T2 = bytes2.get(bytes2.position());
      if (T1 != T2)
        return (T1 - T2);

      // compare values                                                                                                                                                                                                                                                       
      return ByteBufferUtil.compareUnsigned(bytes1, bytes2);
    }
  }

The subcolumn is similar...just a UUID with a type byte prefix:

  public void validate(ByteBuffer bytes)
    throws MarshalException
  {
    if(bytes.remaining() == 0)
      return;

    validateDataType(bytes.get(bytes.position()));
    if((bytes.remaining() - 1) == 0)
      return;
    else if((bytes.remaining() - 1) != 16)
      throw new MarshalException("UUID value must be exactly 16 bytes");
  }

  public int compare(ByteBuffer bytes1, ByteBuffer bytes2)
  {
    if (bytes1.remaining() == 0)
      return bytes2.remaining() == 0 ? 0 : -1;
    else if (bytes2.remaining() == 0)
      return 1;
    else
    {
      // compare type bytes                                                                                                                                                                                                                                                   
      byte T1 = bytes1.get(bytes1.position());
      byte T2 = bytes2.get(bytes2.position());
      if (T1 != T2)
        return (T1 - T2);

      // compare values                                                                                                                                                                                                                                                       
      UUID U1 = getUUID(bytes1, bytes1.position()+1);
      UUID U2 = getUUID(bytes2, bytes2.position()+1);
      return U1.compareTo(U2);
    }
  }

  static UUID getUUID(ByteBuffer bytes, int pos)
  {
    long msBits = bytes.getLong(pos);
    long lsBits = bytes.getLong(pos+8);
    return new UUID(msBits, lsBits);
  }

All of my buffer reads are done by index, the position shouldn't be changing at all.

Abe Sanderson

On Sat, Apr 16, 2011 at 5:38 PM, aaron morton <aaron@thelastpickle.com> wrote:
Can you run the same request as a get_slice naming the column in the SlicePredicate and see what comes back ?

Can you reproduce the fault with logging set at DEBUG and send the logs ?

Also, whats the compare function like for your custom type ?

Cheers
Aaron


On 16 Apr 2011, at 07:34, Abraham Sanderson wrote:

> I'm having some issues with a few of my ColumnFamilies after a cassandra upgrade/import from 0.6.1 to 0.7.4.  I followed the instructions to upgrade and everything seem to work OK...until I got into the application and noticed some wierd behavior.  I was getting the following stacktrace in cassandra occassionally when I did get operations for a single subcolumn for some of the Super type CFs:
>
> ERROR 12:56:05,669 Internal error processing get
> java.lang.AssertionError
>         at org.apache.cassandra.thrift.
> CassandraServer.get(CassandraServer.java:300)
>         at org.apache.cassandra.thrift.Cassandra$Processor$get.process(Cassandra.java:2655)
>         at org.apache.cassandra.thrift.Cassandra$Processor.process(Cassandra.java:2555)
>         at org.apache.cassandra.thrift.CustomTThreadPoolServer$WorkerProcess.run(CustomTThreadPoolServer.java:206)
>         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
>         at java.lang.Thread.run(Thread.java:636)
>
> The assertion that is failing is the check that only one column is retrieved by the get.  I did some debugging with the cli and a remote  debugger and found a few interesting patterns.  First, the problem does not seem consistently duplicatable.  If one supercolumn is affected though, it will happen more frequently for subcolumns that when sorted appear at the beginning of the range.  For columns near the end of the range, it seems to be more intermittent, and almost never occurs when I step through the code line by line.  The only factor I can think of that might cause issues is that I am using custom data types for all supercolumns and columns.  I originally thought I might be reading past the end of the ByteBuffer, but I have quadrupled checked that this is not the case.
>
> Abe Sanderson