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From Guillermo Winkler <gwink...@inconcertcc.com>
Subject Re: Data Modelling Suggestions
Date Thu, 23 Aug 2012 18:28:25 GMT
I think you need another CF as index.

user_itemid -> timestamped column_name

Otherwise you can't guess what's the timestamp to use in the column name.

Anyway I would prefer storing the item-ids as column names in the main
column family and having a second CF for the order-by-date query only with
the pair timestamp_itemid. That way you can add later other query
strategies without messing with how you store the item information.

Maybe you can solve it with a secondary index by timestamp too.

Guille


On Thu, Aug 23, 2012 at 7:26 AM, Roshni Rajagopal <
Roshni.Rajagopal@wal-mart.com> wrote:

> Hi,
>
> Need some help on a data modelling question. We're using Hector & Datastax
> Enterprise 2.1.
>
>
> I want to associate a list of items for a user. It should be sorted on the
> time added. And items can be updated (quantity of the item can be changed),
> and items can be deleted.
> I can model it like this so that its denormalized and I get all my
> information in one go from one row, sorted by time added. I can use
> composite columns.
>
> Row key: User Id
> Column Name: TimeUUID:item ID: Item Name: Item Description: Item Price:
> Item Qty
> Column Value : Null
>
> Now, how do I handle manipulations
>
>  1.  Add new item :Easy , just a new column
>  2.  Add exiting item or modify qty: I want to get to the correct column
> to update . Can I search by second column in the composite column (equals
> condition) & update the column name itself to reflect new TimeUUID and qty?
>  Or would it be better to just add it as a new column and always use the
> latest column for an item in the application code and delete duplicates in
> the background.
>  3.  Delete item: Can I search by second column in the composite column to
> find the correct column to delete?
>
> I was trying to find hector examples where we search for second column in
> a composite column, but I couldn't find any good one. Im not sure if its
> possible.…if you have any do have any example please share.
>
> Regards,
> Roshni
>
>
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