@Roshan Yes, I thought about that, but then I wouldn't be able to use the Random Partitioner.
@Aaron Do you mean like this: 'timeUUID+ row_key' as the supercolumn names? then when retriving the row_key from this column name, will I be required to parse the name ? How do I do that exactly ? >Some issues: >- Will you have time collisions ? No I wont be mostly having time collisions. If they happen in 1% case, I dont mind. >- Not sure what your are storing in the super columns, but their are >limitations. I would be storing maximum 5 subcolumns inside and would be retrieving them altogether. >- If you are using cassandra 0.7, have you looked at the secondary indexes ? Yes I did but I think they are not helpful in my case. This is what I am trying to do : ****** This is from an older post that I made earlier on the mailing list:- I am working on a project of Questions/answers forum that allows a user to follow questions on certain topics from his followies. I want to build user's news-feed that comprises of only those questions that have been posted by his followies & tagged on the topics that he is following. Simple news-feed design that shows all the posts from network would be easy to design using Cassandra by executing fast writes to all followers of a user about the post from user. But for my application, there is an additional filter of 'followed topics', (ie, the user receives posts "created by his followies" && "on topics user is following") I was thinking of implementing this way: Initially writing to all followers, the postID of posts from their network, by adding a supercolumn to the rows of all followers in the News-feed supercolumnfamily, with supercolumn name as timestamp(for sort by time) and 5 sub-columns containing the topic tags of that post. At the read time, compare subcolumn values with the topics user is following, if they match then show the post. (I would be required to fetch the list of followed topics of the user at read time, hence should I store the topic list as a supercolumn in this Newsfeed supercolumnfamily only?) An important point to note that, often, the posts will have zero subcolumn which would mean that this post has to be shown without validating with the user's list of followed topics. There is another view for the users which allows them to see all the posts from their followies(without topic filters). In this case no checking of subcolumns for topics will be performed. I got good insights from Tyler on this, but he was recommending me an approach which although would be beneficial for reads performance, but by way of too much denormalizing like 70-80x. I currently fear that approach and would like to test upon this. ****** any comments, feedback greatly appreciated.. thanks so much! On 1/14/11, Roshan Dawrani <roshandawr...@gmail.com> wrote: > It's possible that I am misunderstanding the question in some way. > > The row keys can be Time UUIDs and with those row keys as column names, u > can use comparator TIMEUUIDTYPE to have them sorted by time automatically. > > On Fri, Jan 14, 2011 at 9:18 AM, Aaron Morton > <aa...@thelastpickle.com>wrote: > >> You could make the time an a fixed width integer and prefix your row keys >> with it, then set the comparotor to ascii or utf. >> >> Some issues: >> - Will you have time collisions ? >> - Not sure what your are storing in the super columns, but their are >> limitations http://wiki.apache.org/cassandra/CassandraLimitations >> <http://wiki.apache.org/cassandra/CassandraLimitations>- If you are using >> cassandra 0.7, have you looked at the secondary indexes ? >> http://www.riptano.com/blog/whats-new-cassandra-07-secondary-indexes >> >> <http://www.riptano.com/blog/whats-new-cassandra-07-secondary-indexes>If >> you provide some more info on the problem your trying to solve we may be >> able to help some more. >> >> Cheers >> Aaron >> >> >> On 14 Jan, 2011,at 04:27 PM, Aklin_81 <asdk...@gmail.com> wrote: >> >> I would like to keep the reference of other rows as names of super >> column and sort those super columns according to time. >> Is there any way I could implement that ? >> >> Thanks in advance! >> >> > > > -- > Roshan > Blog: http://roshandawrani.wordpress.com/ > Twitter: @roshandawrani <http://twitter.com/roshandawrani> > Skype: roshandawrani > > <#> > <#> > <#> <#> >
