well it won't be a range, it will be random key lookups.

On Tue, Jun 15, 2010 at 8:44 AM, Gary Dusbabek <gdusbabek@gmail.com> wrote:
On Tue, Jun 15, 2010 at 04:29, S Ahmed <sahmed1020@gmail.com> wrote:
> If you store only the key mappings in a column family, for custom ordering
> of rows etc. for things like:
> friends = {
>
>    user_id : { friendid1, friendid2, ....}
> }
> or
> topForumPosts = {
>
>     forum_id1 : { post2343, post32343, post32223, ...}
> }
>
> Now on friends page or on the top_forum_posts page you will get back a list
> of post_ids, you will then have to perform lookups on the main 'posts' CF to
> get the actual data.  So if a page is displaying 10, 25, or 50 posts you
> will have 10, 25 or 50 key based lookups for each page view.
> Is this the suggested way?  i.e. a look based on a slice to get a list of
> post_id's, then a seperate call to actually fetch the data for the given
> entity.
> Or is cassandra so fast that 50 key based calls is no reason to worry?

You should look at using either multi_get_slice or get_range_slices.
You'll save on network trips and the amount of work required of the
cluster.

Gary.