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From Tyler Hobbs <>
Subject Re: Read Performance / Schema Design
Date Thu, 27 Oct 2011 05:01:11 GMT
On Wed, Oct 26, 2011 at 9:35 PM, Ben Gambley <>wrote:

> Hi Everyone
> I have a question with regards read performance and schema design if
> someone could help please.
> Our requirement is to store per user, many unique results (which is
> basically an attempt at some questions ..) so I had thought of having the
> userid as the row key and the result id as columns.
> The keys  for the result ids are maintained in a separate location so are
> known without having to perform any additional lookups.
> My concern is that over time reading a single result would incur the
> overhead of reading the entire row from disk so gradually slow things down.
> So I was considering if changing the row key to *userid + result id* would
> be a better solution ?

Do you regularly need to read all of the results for a given userid?  If
not, go with the user_id + result_id approach. It will be more efficient for
single-result lookups.

Tyler Hobbs
DataStax <>

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