Only row key in a Cassandra column family

Question

I'm using Cassandra 1.1.8 and today I saw in my keyspace a column family with the following content

 SELECT * FROM challenge;
 KEY
----------------------------
 49feb2000100000a556522ed68  
 49feb2000100000a556522ed74  
 49feb2000100000a556522ed7a   
 49feb2000100000a556522ed72   
 49feb2000100000a556522ed76   
 49feb2000100000a556522ed6a   
 49feb2000100000a556522ed70   
 49feb2000100000a556522ed78   
 49feb2000100000a556522ed6e   
 49feb2000100000a556522ed6c   

So, only rowkeys. Yesterday those rows were there and I ran some deletions (exactly on those rows). I'm using Hector

Mutator<byte []> mutator = HFactory.createMutator(keyspace, BYTES_ARRAY_SERIALIZER)
    .addDeletion(challengeRowKey(...), CHALLENGE_COLUMN_FAMILY_NAME)
    .execute();

This is a small development and test environment on a single machine / single node so I don't believe the hardware details are relevant. Probably I'm doing something stupid or I didn't get the point about how things are working, but as far I understood the rows above are no valid... column name and column value coordinates are missing so there are no valid cells (rowkey / column name / column value)...is that right?

I read about ghost reads but I think this is a scenario in a distribuited environment...is that valid after one day and on a single Cassandra node??

Answer 1

From http://www.datastax.com/docs/1.0/dml/about_writes#about-deletes

"The row key for a deleted row may still appear in range query results. When you delete a row in Cassandra, it marks all columns for that row key with a tombstone. Until those tombstones are cleared by compaction, you have an empty row key (a row that contains no columns). These deleted keys can show up in results of get_range_slices() calls. If your client application performs range queries on rows, you may want to have if filter out row keys that return empty column lists."