I'm very new to Cassandra, but I'll pitch in my $0.02.

Row look-ups are super fast, why do you think it would be more efficient to store these two rows "together" in the super column method you describe?

Why would you not just look-up the rows, one after the other?

If I understand correctly, you have post_ids, user_ids, and groups. A group contains user_ids (people posting to the group) and post_ids (posts made to that group)?

So I write a post to a group. You'd add this post_id to the row holding all the posts for this group (this might be bad if the number of posts/columns grows huge). You'd then have another row associated with the group where you'd insert my user_id. Am I close to what you want?

If you can give a more concrete example, I (or someone more familiar with Cassandra) could give you more help on designing a schema.

Bill-

On 01/29/2011 01:48 PM, Ertio Lew wrote:
Could someone please point me in right direction by commenting on the above 
ideas ?

On Fri, Jan 28, 2011 at 11:50 PM, Ertio Lew <ertio...@gmail.com
<mailto:ertio...@gmail.com>> wrote:

    Hi,

    I have two kinds of data that I would like to fit in one super column
    family; I am trying this, for the reasons of implementing fast
    database retrievals by combining the data of two rows into just one
    row.

    First kind of data, in supercolumn family, is named with timeUUIDs as
    supercolumn names; Think of this as, the postIds of posts in a Group.
    These posts will need to be sorted by time (so that list of latest
    posts is retrieved). Thus each post has one supercolumn each with name
    as (timeUUID+userID) and sorted by timeUUIDtype.

    Second kind of data would be just a single supercolumn containing
    columns of userId of all members in a group(very small). (The no of
    members in group will be around 40-50 max). The name of this single
    supercolumn may be kept suitable(perhaps max. time in future ) so as
    to keep this supercolumn to the beginning.

    (The supercolumns are required as we need to store some additional
    data in the columns of 1st kind of data).

    So is it recommended to store these two types of data (not related to
    each other but need to be retrieved together) in one super column
    family ?


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