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From Peter Chang <pete...@gmail.com>
Subject Re: Model Question
Date Thu, 25 Mar 2010 16:45:04 GMT
Do you mean on the client? It really depends on how many items you're
sorting. In terms of computer runtime, client-side will always likely be
faster but if you take into account bandwidth speeds having a pre-sorted
list will be better for large lists.

Creating 0-padded numbers is pretty straightforward. That's how people sort
number values (stored as strings) in Simple DB.


On Thu, Mar 25, 2010 at 1:32 AM, Colin Vipurs <zodiaczx6@gmail.com> wrote:

> Peter,
>
> Do you think 0-padding the entries would be more efficient than just
> implementing your own comparator?
>
> On Wed, Mar 24, 2010 at 10:57 PM, Peter Chang <peter78@gmail.com> wrote:
> > If there's not much overhead, I recommend client side as well.
> > Otherwise, you can only sort on column. Therefore, you could create some
> > sort of inverted index based on the message count.
> > User 1 sent 50 messages.
> > User 2 sent 10 messages.
> > User 3 sent 25 messages.
> > Then store a separate index that looks like:
> >   ->  50-User-1-Key
> >   ->  25-User-2-Key
> >   ->  10-User-2-Key
> > You'd also have to 0-pad your count so that numbers are correctly
> compared
> > (12 is less than 110) since you'll have to use some lexical-based
> sorting.
> >
> >
> > On Wed, Mar 24, 2010 at 1:36 PM, Erez Efrati <erezef@gmail.com> wrote:
> >>
> >> Hi,
> >> I can't figure out how to use model the following using column family
> and
> >> the way the columns are sorted (by their name).
> >> Lets say I have a list of users and for each user I wish to display a
> list
> >> of all the friends he has ordered by the number of messages they sent
> him so
> >> far (desc from most to least).
> >> I can't see how this is going to work since the columns sorting is
> always
> >> by the name of the column and not its value. I thought of having a row
> for
> >> each user and the columns will be the friends that email him. But the
> column
> >> name needs to be the number of messages to be sorted and the value will
> be
> >> the friend's user ID. But then, when a friend is sending a message to
> >> another user how do I increment his count of message he sent so far to
> that
> >> user?
> >> How can I model this with Cassandra? Is it possible?
> >> Thanks in advance,
> >> Erez Efrati
> >
>
>
>
> --
> Maybe she awoke to see the roommate's boyfriend swinging from the
> chandelier wearing a boar's head.
>
> Something which you, I, and everyone else would call "Tuesday", of course.
>

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