Hello, Consistency is declared at the statement level, i.e. batch level when writing, but enforced at each batch row level. My understanding is that each batch (and all of it's contents) will be controlled through a specific CL declaration. So batch A could use a CL of QUORUM while batch B could use a CL of ONE.
The detail that may help sort this out for you is that batch statements do not provide isolation guarantees: www.datastax.com/documentation/cql/3.0/cql/cql_reference/batch_r.html. This means that you write the batch as a batch but the reads are per row. If you are reading records contained in the batch, you will read results of partially updated batches. Taking this into account for your second question, you should expect that your read CL will preform as it would for any individual row mutation. Hope this helps. Jonathan Jonathan Lacefield Solutions Architect, DataStax (404) 822 3487 <http://www.linkedin.com/in/jlacefield> <http://www.datastax.com/what-we-offer/products-services/training/virtual-training> On Sat, Mar 15, 2014 at 12:23 PM, Drew Kutcharian <d...@venarc.com> wrote: > Hi Guys, > > How do Atomic Batches and Consistency Level relate to each other? More > specifically: > > - Is consistency level set/applicable per statement in the batch or the > batch as a whole? > > - Say if I write a Logged Batch at QUORUM and read it back at QUORUM, what > can I expect at normal, single node replica failure or double node replica > failure scenarios? > > Thanks, > > Drew
