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From Sandeep Tata <sandeep.t...@gmail.com>
Subject Re: Row vs CF
Date Wed, 22 Apr 2009 16:32:44 GMT
Having multiple CFs in a row could be useful for writes. Consider the
case when you use one CF to store the data and another to store some
kind of secondary index on that data. It will be useful to apply
updates to both families atomically.

On the read path, I agree -- I don't know if there are many useful
scenarios for reading from multiple CFs in one go. An app that is
doing this is probably not modeled correctly.

On Wed, Apr 22, 2009 at 8:54 AM, Jonathan Ellis <jbe@familyellis.org> wrote:
> In a bunch of places in the code we wrap a CF in a Row object,
> basically a key + multiple CFs.  But currently only a single
> ColumnFamily will ever be in a Row object.  (At least in the Rows
> involved in a client read op.  Maybe Rows are used internally in other
> places with multiple CFs.  But I am concerned with the read path
> here.)
>
> Is this an example where we should apply YAGNI?
> (http://en.wikipedia.org/wiki/You_Ain%27t_Gonna_Need_It)  It seems to
> me that if the definition of a CF is, "this is data that is logically
> or otherwise related" then adding an API to request multiple CFs at
> once is unnecessary.  (If you really need data from multiple CFs
> frequently, your data model is broken and you should combine the CFs;
> if you need it infrequently, the overhead from doing multiple queries
> is not a big deal.)
>
> Thoughts?
>
> -Jonathan
>

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