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Date: Sat, 22 Sep 2012 21:24:28 +0200
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Subject: Re: what's the order of docs/keys going into reduce func?
From: Octavian Damiean <mainerror@gmail.com>
To: user@couchdb.apache.org
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I don't understand a thing, sorry. You might have to rephrase it.

On Sat, Sep 22, 2012 at 9:23 PM, svilen <az@svilendobrev.com> wrote:

> > > no, yours is just a simple filter, and it will always have them all
> > > as they all start from being off.
> >
> > I am having trouble understanding this.  What do you mean by "simple
> > filter"?  A view is a view, not a filter.  Once the view is set up it
> > will always be up-to-date.
>
> take 2 steps back and reread my question from start. the important
> notions are "multiple values" with "same-keys" and their "current
> state-per-key". that is what i want.
>
> svil
>
> > On Sat, Sep 22, 2012 at 11:57 AM, svilen <az@svilendobrev.com> wrote:
> >
> > > no, yours is just a simple filter, and it will always have them all
> > > as they all start from being off.
> > >
> > > and it is somewhat simplified example. The original thing has
> > > multiple states, and i want the last/current one - whatever it is.
> > >
> > > say, i want to reduce things like assigning ( a=1, a=2, b=1, b=2,
> > > a=3 ) into flat last-state ( a=3, b=2 )
> > >
> > > how to do that?
> > >
> > > svil
> > >
> > >
> > > On Sat, 22 Sep 2012 11:43:14 -0700
> > > Mark Hahn <mark@hahnca.com> wrote:
> > >
> > > > >  i want a view for all lamps that the currently off.
> > > >
> > > > You view is wrong.  You should only emit when the lamp is off.
> > > >
> > > > Also, you should always return a value in reduce.  Returning null
> > > > will screw things up.
> > > >
> > > > I would start by fixing these problems and then go from there.
> > > >
> > > >
> > > > On Sat, Sep 22, 2012 at 3:05 AM, svilen <az@svilendobrev.com>
> > > > wrote:
> > > >
> > > > > say i have some lamp status monitoring records, i.e.
> > > > >
> > > > >  { "seq": 1, "name": "a", },
> > > > >  { "seq": 2, "name": "b", },
> > > > >  { "seq": 2, "name": "a", "on": true},
> > > > >  { "seq": 3, "name": "a", },
> > > > >  { "seq": 7, "name": "a", "on": true},
> > > > >
> > > > > ...
> > > > >
> > > > > where default state is off, and when on, there's extra bool
> > > > > attribute for it. Records are sequenced (in time) by some .seq
> > > > > param. And there's many other here-irrelevant attributes.
> > > > >
> > > > > say i want a view for all lamps that the currently off.
> > > > >
> > > > > so, something like:
> > > > >
> > > > > map_func: function( doc) {
> > > > >   if (doc.type == 'lamp') emit( [doc.name, doc.seq], doc );
> > > > > }
> > > > >
> > > > > reduce_func: function( keys, values, rereduce) {
> > > > >   var v = values[ values.length-1];
> > > > >   if (v == null || v.on) return null;
> > > > >   return v;
> > > > > }
> > > > >
> > > > > always used with group_level= 1
> > > > >
> > > > > but i get the very first state instead of very last state...
> > > > >
> > > > > and in the debug-log, i see that the keys passed to reduce are
> > > > > reversed!
> > > > >
> > > > > so i have to use descending=True, and only then it works
> > > > > correctly.
> > > > >
> > > > > the question is, is this expected, or is the default order
> > > > > defined somewhere else, or what?
> > > > >
> > > > > ciao
> > > > > svil
> > > > >
> > >
>

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