I'm also seeing an issue with not being able to iterate over all keys in Cassandra 0.6.4.  In my unit test I create 20 keys (0-19) and iterate with a batch size of 6.  This is what I get.

 

Cassandra 0.6.4

start key: ""

9, 14, 4, 15, 11, 18

start key: 18

18, 7, 17, 7, 17

start key:17

17

 

Cassandra 0.6.3

start key: ""

3, 6, 5, 19, 10, 0

start key: 0

0, 8, 2, 16, 13, 1

start key: 1

1, 12, 9, 14, 4, 15

start key: 15

15, 11, 15, 11, 18, 7

start key: 7

7, 17, 7, 17

 

In both versions I get duplicates but in 0.6.4 I don't get the complete set of keys back.  The complete set is returned in 0.6.3.