The principle in Cassandra modeling is that for each query, you should denormalize your data at write time such that you can get the data for that query from a single row.
The best explanation so far is at http://www.rackspacecloud.com/blog/2010/05/12/cassandra-by-example/ On Tue, Jun 22, 2010 at 1:13 PM, S Ahmed <sahmed1...@gmail.com> wrote: > Converting a Forum application to cassandra's data model. > > Tables: > > Posts [postID, threadID, userID, subject, body, created, lastmodified] > > So this table contains the actual question subject and body. > > When a user logs in, they want to see a list of their questions, and also > order by the last-modified date (to see if people responed to their > question). > > How would you do this best in Cassandra, seeing as the question/answer text > is stored in another table. > > I know you could make a CF like: > > userID { postID1, postID2, ...} > > And somehow order by last-modified, but then on the actual web page you > would have to first query for postID's owned by the user, and orderd by > last-modified. > > THEN you would have to fetch the post data from the posts collection. > > Is this the only way? I mean other than repeating the post subject+body in > the user-to-postID index CF. > > > -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com
