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From Kamyar Navidan <kamya...@gmail.com>
Subject Re: newbie question: reduce/group_level
Date Sun, 06 Dec 2009 06:25:00 GMT
Thank you for your response. So in general [x1, x2, ... , xn-1]
gets precedence over [x1, x2, ... , xn-1, xn] where x1...xn-1 is identical.
Am I getting this right?

On Sun, Dec 6, 2009 at 9:01 AM, Chris Anderson <jchris@apache.org> wrote:

> On Sat, Dec 5, 2009 at 8:55 PM, Kamyar Navidan <kamyar.n@gmail.com> wrote:
> > Reading through Couchdb: The Definitive Guide I came across this section
> in
> > chapter 06 :
> >
> > In the blog app, we use group_level reduce queries to compute the count
> of
> >> comments both on a per-post and total basis, achieved by querying the
> same
> >> view index with different methods. With some array keys, and assuming
> each
> >> key has the value 1:
> >
> >
> >> ["a","b","c"]
> >
> > ["a","b","e"]
> >
> > ["a","c","m"]
> >
> > ["b","a","c"]
> >
> > ["b","a","g"]
> >
> >
> >> The reduce view:
> >
> >
> >> function(keys, values, rereduce) {
> >
> >  return sum(values)
> >
> > }
> >
> >
> >> returns the total number of rows between the start and end key. So with
> >> startkey=["a","b"]&endkey=["b"] (which includes the first 3 of the above
> >> keys) the result would equal 3.
> >
> >
> > Earlier in chapter it is stated that:
> >
> > The startkey and and endkey parameters specify an inclusive range on
> which
> >> we can search.
> >
>
> There is an inclusive_endkey=true http query parameter you can use.
>
> >
> > So how come the fourth and fifth rows that satisfy endkey=["b"] condition
> > are not included in results? I guess I am missing something here. Can
> > somebody please clarify this for me.
> >
>
> In this case, only the keys:
>
> ["a","b","c"]
> ["a","b","e"]
> ["a","c","m"]
>
> are included in the range.
>
> the key ["b","a","c"] comes after ["b"] so it is not included. ["b"]
> itself would match.
>
> Chris
>
>
>
>
>
> --
> Chris Anderson
> http://jchrisa.net
> http://couch.io
>

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