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From Voytek Jarnot <>
Subject Re: Read efficiency question
Date Tue, 27 Dec 2016 16:12:53 GMT
Thank you Oskar.  I think you may be missing the double parentheses in the
first example - difference is between partition key of (key1, key2, key3)
and (key1, key2).  With that in mind, I believe your answer would be that
the first example is more efficient?

Is this essentially a case of the coordinator node being able to exactly
pinpoint a row (first example) vs the coordinator node pinpointing the
partition and letting the partition-owning node refine down to the right
row using the clustering key (key3 in the second example)?

On Tue, Dec 27, 2016 at 10:06 AM, Oskar Kjellin <>

> The second one will be the most efficient.
> How much depends on how unique key1 is.
> In the first case everything for the same key1 will be on the same
> partition.  If it's not unique at all that will be very bad.
> In the second case the combo of key1 and key2 will decide what partition.
> If you don't ever have to find all key2 for a given key1 I don't see any
> reason to do case 1
> > On 27 Dec 2016, at 16:42, Voytek Jarnot <> wrote:
> >
> > Wondering if there's a difference when querying by primary key between
> the two definitions below:
> >
> > primary key ((key1, key2, key3))
> > primary key ((key1, key2), key3)
> >
> > In terms of read speed/efficiency... I don't have much of a reason
> otherwise to prefer one setup over the other, so would prefer the most
> efficient for querying.
> >
> > Thanks.

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