Hi,
I have been playing with get_slice() in cassandra 0.4, and I have noticed the
following issue:
When the column name is a Long, multiple invocations of get_slice() returns
different values (sometimes none at all).
After a bit of a digging, I noticed that package
org.apache.cassandra.db.marshal.LongType.java deserializes longs with a little
endian byte order. The default java byte ordering is big endian. This seems to
impact the way SliceQueryFilter iterates over the columns. Once I changed
LongType to use big endian byte order, the problem went away for me.
Was wondering if this was a known issue (or an issue at all - cropped up by how
I am using it).
My setup is as below:
- Cassandra 0.4
- Running on Mac OS Leopard 10.5.8, JDK 1.6.0_13
- Storage config has one keyspace, with one (simple) column family :
<ColumnFamily CompareWith="LongType" Name="revs"/>
- When inserting data, I convert the long (my column name) to byte array as
such:
ByteArrayOutputStream bos = null;
DataOutputStream dos = null;
try {
bos = new ByteArrayOutputStream();
dos = new DataOutputStream(bos);
dos.writeLong(l);
dos.flush();
byte[] ret = bos.toByteArray();
return ret;
- When querying, I use the below: (I use thrift. The example uses reverse
order, I tried both ways)
ColumnParent column_parent = new ColumnParent("revs", null);
SlicePredicate predicate = new SlicePredicate();
predicate.setSlice_range(new
SliceRange(CarmotUtil.getBytes(System.currentTimeMillis()),
CarmotUtil.getBytes(0l), true, 1000));
List<ColumnOrSuperColumn> ret = cl.get_slice("Objects", id,
column_parent, predicate, 1);
I would appreciate any feedback/insights on this. I can provide more details as
needed.
Thanks,
Bhaskar
