We encounter this weird problem on Cassandra 0.8.6. Basically, an existing row cannot be inserted with a new column. But a brand new row has no problem. There is no errors in log. We tried rolling-restart each Cassandra nodes. And then a row having this problem previously becomes good. But then we found other existing rows show this problem. We haven't tried to delete all data files on all nodes to start from scratch yet (and hope we don't need to):
[cassandra@cl01 bin]$ ./cassandra-cli -h localhost
Connected to: "Test Local Cluster" on localhost/9160
Welcome to the Cassandra CLI.
Type 'help;' or '?' for help.
Type 'quit;' or 'exit;' to quit.
[default@unknown] use mytest;
Authenticated to keyspace: mytest
[default@mytest] assume mycf comparator as long;
Assumption for column family 'mycf' added successfully.
[default@mytest] assume mycf validator as utf8;
Assumption for column family 'mycf' added successfully.
[default@mytest] assume mycf keys as utf8;
Assumption for column family 'mycf' added successfully.
[default@mytest] get mycf['old'];
Returned 0 results.
[default@mytest] set mycf['old'][100]='abc';
Value inserted.
[default@mytest] get mycf['old'];
Returned 0 results.
[default@mytest] set mycf['new'][100]='def';
Value inserted.
[default@mytest] get mycf['new'];
=> (column=100, value=def, timestamp=1321242812229000)
Returned 1 results.
