Thanks victor! Aren't there any good ways by using Cassandra alone ?
On Wed, May 18, 2011 at 11:41 PM, openvictor Open <openvic...@gmail.com>wrote: > Have you thought about user another kind of Database, which supports > volative content for example ? > > I am currently thinking about doing something similar. The best and > simplest option at the moment that I can think of is Redis. In redis you > have the option of querying keys with wildcards. Your problem can be done by > just inserting an UUID into Redis for a certain amount of time ( the best is > to tailor this amount of time as an inverse function of the number of keys > existing in Redis). > > *With Redis* > What I would do : I cut down time in pieces of X minutes ( 15 minutes, for > example by truncating a timestamp). Let timestampN be the timestamp for the > period of time ( [N,N+15] ), let Topic1 Topic2 be two topics then : > > One or more people will view Topic 1 then Topic2 then again Topic1 in this > period of 15 minutes > (HINCRBY is the Increment) > H <http://redis.io/commands/hincrby>INCRBY<http://redis.io/commands/hincrby> > topics:Topic1:timestampN > viewcount 1 > H <http://redis.io/commands/hincrby>INCRBY<http://redis.io/commands/hincrby> > topics:Topic2:timestampN > viewcount 1 > H <http://redis.io/commands/hincrby>INCRBY<http://redis.io/commands/hincrby> > topics:Topic1:timestampN > viewcount 1 > > Then you just query in the following way : > > MGET <http://redis.io/commands/mget> topics:*:timestampN > > * is the wildcard, you order by viewcount and you have what you are asking > for ! > This is a simplified version of what you should do but personnally I really > like the combination of Cassandra and Redis. > > > Victor > > 2011/5/18 Aditya Narayan <ady...@gmail.com> > >> I would arrange for memtable flush period in such a manner that the time >> period for which these most viewed discussions are generated equals the >> memtable flush timeperiod, so that the entire row of most viewed discussion >> on a topic is in one or maximum two memtables/ SST tables. >> This would also help minimize several versions of the same column in the >> row parts in different SST tables. >> >> >> >> On Wed, May 18, 2011 at 11:04 PM, Aditya Narayan <ady...@gmail.com>wrote: >> >>> ************* >>> For a discussions forum, I need to show a page of most viewed >>> discussions. >>> >>> For implementing this, I maintain a count of views of a discussion & when >>> this views count of a discussion passes a certain threshold limit, the >>> discussion Id is added to a row of most viewed discussions. >>> >>> This row of most viewed discussions contains columns with Integer names & >>> values containing serialized lists of Ids of all discussions whose views >>> count equals the Integral name of this column. >>> >>> Thus if the view count of a discussion increases I'll need to move its >>> 'Id' from serialized list in some column to serialized list in another >>> column whose name represents the updated views count on that discussion. >>> >>> Thus I can get the most viewed discussions by getting the appropriate no >>> of columns from one end of this Integer sorted row. >>> >>> ************ >>> >>> I wanted to get feedback from you all, to know if this is a good design. >>> >>> Thanks >>> >>> >>> >>> >>> >>> >> >
