How would I route the messages to a specific partition? On 27 Dec 2016 10:25 a.m., "Asaf Mesika" <asaf.mes...@gmail.com> wrote:
> There is a much easier approach: your can route all messages of a given Id > to a specific partition. Since each partition has a single writer you get > the ordering you wish for. Of course this won't work if your updates occur > in different hosts. > Also maybe Kafka streams can help shard the based on item Id to a second > topic > On Thu, 22 Dec 2016 at 4:31 Ali Akhtar <ali.rac...@gmail.com> wrote: > > > The batch size can be large, so in memory ordering isn't an option, > > unfortunately. > > > > On Thu, Dec 22, 2016 at 7:09 AM, Jesse Hodges <hodges.je...@gmail.com> > > wrote: > > > > > Depending on the expected max out of order window, why not order them > in > > > memory? Then you don't need to reread from Cassandra, in case of a > > problem > > > you can reread data from Kafka. > > > > > > -Jesse > > > > > > > On Dec 21, 2016, at 7:24 PM, Ali Akhtar <ali.rac...@gmail.com> > wrote: > > > > > > > > - I'm receiving a batch of messages to a Kafka topic. > > > > > > > > Each message has a timestamp, however the messages can arrive / get > > > processed out of order. I.e event 1's timestamp could've been a few > > seconds > > > before event 2, and event 2 could still get processed before event 1. > > > > > > > > - I know the number of messages that are sent per batch. > > > > > > > > - I need to process the messages in order. The messages are basically > > > providing the history of an item. I need to be able to track the > history > > > accurately (i.e, if an event occurred 3 times, i need to accurately log > > the > > > dates of the first, 2nd, and 3rd time it occurred). > > > > > > > > The approach I'm considering is: > > > > > > > > - Creating a cassandra table which is ordered by the timestamp of the > > > messages. > > > > > > > > - Once a batch of messages has arrived, writing them all to > cassandra, > > > counting on them being ordered by the timestamp even if they are > > processed > > > out of order. > > > > > > > > - Then iterating over the messages in the cassandra table, to process > > > them in order. > > > > > > > > However, I'm concerned about Cassandra's eventual consistency. Could > it > > > be that even though I wrote the messages, they are not there when I try > > to > > > read them (which would be almost immediately after they are written)? > > > > > > > > Should I enforce consistency = ALL to make sure the messages will be > > > available immediately after being written? > > > > > > > > Is there a better way to handle this thru either Kafka streams or > > > Cassandra? > > > > > >
