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Date: Wed, 5 Jun 2013 22:21:21 -0400 (EDT)
From: "John R. Frank" <jrf@mit.edu>
To: user@cassandra.apache.org
Subject: smallest/largest UUIDs for LexicalUUIDType
Message-ID: <alpine.DEB.2.00.1306052210490.10290@computableinsights.com>
User-Agent: Alpine 2.00 (DEB 1167 2008-08-23)
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C*,

I'm trying to use composite column names to organize 10**8 records.  Each 
record has a unique pair of UUIDs.  The first UUID is often repeated, so I 
want to use column_start and column_finish to find all the records that 
have a given UUID as the first UUID in the pair.

I thought a simple way to get *all* of the columns would be to use

  start  = uuid.UUID(int=0)        -> 00000000-0000-0000-0000-000000000000
  finish = uuid.UUID(int=2**128-1) -> ffffffff-ffff-ffff-ffff-ffffffffffff

But strangely, this fails to find *any* of the columns, and it requires 
that column_reversed=True -- otherwise it raises an error about range 
finish not coming after start.  If I use ints that are much larger/smaller 
than these extremes, then reversed is not required!

Can anyone explain why LexicalUUIDType() does not treat these extremal 
UUIDs like other UUIDs?


Using pycassa v1.9:

     sm = SystemManager(chosen_server)
     sm.create_keyspace(namespace, SIMPLE_STRATEGY, {'replication_factor': '1'})

     family = 'test'
     sm.create_column_family(
         namespace, family, super=False,
         key_validation_class = ASCII_TYPE,
         default_validation_class = BYTES_TYPE,
         comparator_type=CompositeType(LexicalUUIDType(), LexicalUUIDType()),
         #column_name_class = LEXICAL_UUID_TYPE
         )

     pool = ConnectionPool(namespace, config['storage_addresses'],
                           max_retries=1000, pool_timeout=10, pool_size=2, timeout=120)

     cf = pycassa.ColumnFamily(pool, family)
     u1, u2, u3, u4 = uuid.uuid1(), uuid.uuid1(), uuid.uuid1(), uuid.uuid1()

     cf.insert('inbound', {(u3, u3): b'43'})

     start  = uuid.UUID(int=0)
     finish = uuid.UUID(int=2**128-1)
     print start
     print finish
     assert start < u3 < finish
     print cf.get('inbound', column_start=(start,), column_finish=(finish,), column_reversed=True).items()

     sm.close()


Raises:
             if len(list_col_or_super) == 0:
>               raise NotFoundException()
E               NotFoundException: NotFoundException(_message=None)

../../ve/local/lib/python2.7/site-packages/pycassa/columnfamily.py:663: NotFoundException


jrf