In C* 2.1, the new row cache implementation keeps the most recent N partitions in memory, it might be of interest for you: http://www.datastax.com/dev/blog/row-caching-in-cassandra-2-1
On Fri, Jul 18, 2014 at 3:39 AM, Chris Lohfink <clohf...@blackbirdit.com> wrote: > I would say that would work, but since already familiar with storage model > from hbase and trying to emulate it may want to look into thrift > interfaces. They little more similar to hbase interface (not as friendly > to use and you cant use the very useful new client libraries from datastax) > and accesses storage more directly, which is similar to hbases. You have > your column family foo, then just use a composite column to store family, > qualifier, and version in column name with value of column being "value". > row key is your row key. > > --- > Chris Lohfink > > > On Jul 17, 2014, at 6:32 PM, Clint Kelly <clint.ke...@gmail.com> wrote: > > > Hi everyone, > > > > I am trying to design a schema that will keep the N-most-recent > > versions of a value. Currently my table looks like the following: > > > > CREATE TABLE foo ( > > rowkey text, > > family text, > > qualifier text, > > version long, > > value blob, > > PRIMARY KEY (rowkey, family, qualifier, version)) > > WITH CLUSTER ORDER BY (rowkey ASC, family ASC, qualifier ASC, version > DESC)); > > > > Is there any standard design pattern for updating such a layout such > > that I keep the N-most-recent (version, value) pairs for every unique > > (rowkey, family, qualifier)? I can't think of any way to do this > > without doing a read-modify-write. The best thing I can think of is > > to use TTL to approximate the desired behavior (which will work if I > > know how often we are writing new data to the table). I could also > > use "LIMIT N" in my queries to limit myself to only N items, but that > > does not address any of the storage-size issues. > > > > In case anyone is curious, this question is related to some work that > > I am doing translating a system built on HBase (which provides this > > "keep the N-most-recent-version-of-a-cell" behavior) to Cassandra > > while providing the user with as-similar-as-possible an interface. > > > > Best regards, > > Clint > >
