In your example is a little unclear.
If you are writing to a single row and creating columns with user names. Then when you read all the columns for row 1 you will get columns called Dan and Ken.
If you are writing to the same column, let's say called user, then *if* they are send with the same time stamp the greater value when compared by bytes will be used. Ken in this case.
If you app has sections that are highly concurrent try to design them away, or use a locking mechanism outside of casandra, or use another DB.
Hope that helps.
Yes, the same timestamp
2010/12/10 Ryan King <email@example.com>
By "exactly the same" do you mean "with the same timestamp"?
On Fri, Dec 10, 2010 at 12:49 PM, Alvin UW <firstname.lastname@example.org
> I got a consistency problem in Cassandra.
> Given a column family with a record: Id Name
> 1 David
> There are three backups for this column family.
> Assume there are two write operation happens issued by the same application
> by this order: write_one("1", "Dan") ; write_one("1", "Ken").
> What will Read_all("1") get?
> Assume the above two write operations happens exactly the same time in two
> Again what will Read_all("1") get?