Thanks Roshni, I'm not sue how #d will work when users are actually voting on a comment. What happens when two users vote on the same comment simultaneously? How do you update the entries in #d column family to prevent duplicates?
Also #a and #c can be combined together using TimeUUID as comment ids. - Drew On Sep 27, 2012, at 2:13 AM, Roshni Rajagopal <roshni_rajago...@hotmail.com> wrote: > Hi Drew, > > I think you have 4 requirements. Here are my suggestions. > > a) store comments : have a static column family for comments with master data > like created date, created by , length etc > b) when a person votes for a comment, increment a vote counter : have a > counter column family for incrementing the votes for each comment > c) display comments sorted by date created: have a column family with a dummy > row id 'sort_by_time_list', column names can be date created(timeUUID), and > column value can be comment id > d) display comments sorted by number of votes: have a column family with a > dummy row id 'sort_by_votes_list' and column names can be a composite of > number of votes , and comment id ( as more than 1 comment can have the same > votes) > > > Regards, > Roshni > > > Date: Wed, 26 Sep 2012 17:36:13 -0700 > > From: k...@mustardgrain.com > > To: user@cassandra.apache.org > > CC: d...@venarc.com > > Subject: Re: Data Modeling: Comments with Voting > > > > Depending on your needs, you could simply duplicate the comments in two > > separate CFs with the column names including time in one and the vote in > > the other. If you allow for updates to the comments, that would pose > > some issues you'd need to solve at the app level. > > > > On 9/26/12 4:28 PM, Drew Kutcharian wrote: > > > Hi Guys, > > > > > > Wondering what would be the best way to model a flat (no sub comments, > > > i.e. twitter) comments list with support for voting (where I can sort by > > > create time or votes) in Cassandra? > > > > > > To demonstrate: > > > > > > Sorted by create time: > > > - comment 1 (5 votes) > > > - comment 2 (1 votes) > > > - comment 3 (no votes) > > > - comment 4 (10 votes) > > > > > > Sorted by votes: > > > - comment 4 (10 votes) > > > - comment 1 (5 votes) > > > - comment 2 (1 votes) > > > - comment 3 (no votes) > > > > > > It's the sorted-by-votes that I'm having a bit of a trouble with. I'm > > > looking for a roll-your-own approach and prefer not to use secondary > > > indexes and CQL sorting. > > > > > > Thanks, > > > > > > Drew > > > > >
