Some big systems using Cassandra's counters were built (such as Rainbird: http://www.slideshare.net/kevinweil/rainbird-realtime-analytics-at-twitter-strata-2011) and seem to be doing great job.
If you are concerned with performance, then maybe using memory-based store (such as Redis) will better suit your case (as long as it fits in the memory, but considering the data model, I guess it might work). If you are going to stick with Cassandra, then tweaking compaction threshold can make a visible difference on the read performance, at least from what I have seen. You can also consider changing the PRIMARY KEY to ((uid, someid), time) - this will make the partition key out of uid+someid, rather than just someid. Depending on the access pattern, it might help. On Thu, Dec 5, 2013 at 4:44 PM, Christopher Wirt <chris.w...@struq.com>wrote: > I want to build a really simple column family which counts the occurrence > of a single event X. > > > > Once we reach Y occurrences of X the counter resets to 0 > > > > The obvious way to do this is with a counter CF. > > > > CREATE TABLE xcounter1 ( > > id uuid, > > someid int, > > count counter > > ) PRIMARY KEY (uid, someid) > > > > This is how I’ve always done it in the past, but I’ve been told to avoid > counters for various reasons, performance, consistency etc.. > > I’m not too bothered about 100% absolute consistency, however read > performance is certainly a big concern. > > > > So I was thinking to avoid using counters I could do something like this. > > > > CREATE TABLE xcounter2 ( > > id uuid, > > someid int, > > time timeuuid > > ) PRIMARY KEY (uid, someid, time) > > > > Then retrieve all events and count in memory. Delete all id, someid > records once I hit Y. > > > > Or I could > > CREATE TABLE xcounter3 ( > > id uuid, > > someid int, > > time timeuuid, > > Ycount int > > ) PRIMARY KEY (uid, someid, time) > > > > Insert a ‘Ycount’ on each occurrence of the event. > > Only retrieve the last Y value inserted on reading > > Then delete all records once I hit the magic Y value. > > > > > > Anyone have any interesting thoughts or insight on what is likely to give > me the best read performance? > > There will be 100’s of someid to each id. Reads will be 5-10x the writes. > > > > > > Thanks, > > > > Chris >
