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From svilen ...@svilendobrev.com>
Subject Re: what's the order of docs/keys going into reduce func?
Date Sat, 22 Sep 2012 18:57:36 GMT
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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