On Sat, Dec 18, 2010 at 11:02 PM, Kevin Irwig <kevinir...@yahoo.com> wrote:
> Hi, > > Say I have two processes on separate machines, and a Cassandra cluster over > several machines. If the first process writes (insert) to a column while > the > second process reads (get / get_slice / get_range_slices / others?) from > that > column (say the consistency level is QUORUM if that makes a difference), is > the > write "atomic", or could the second process get corrupt (half-written) > data? > What if Cassandra is not a cluster, but runs on a single machine? I'm > currently > using version 0.6.3, but the question is general. > > The write is consistent if consistency level of write is QUORUM and read is QUORUM or according to the popular equation for strong consistency if R + W > N where N = number of replicas, R = consistency level of read, W = consistency level of write On single machine with one node, consistency level of 1 for both R and W will make the write consistent as again 1 + 1 > 1 Cassandra : The definitive guide - is a good resource for most questions besides the wiki and mailing list. http://oreilly.com/catalog/0636920010852 -Adi
