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From Patrick Antivackis <>
Subject Re: Grouping by second value in key
Date Thu, 30 Apr 2009 20:30:35 GMT
Hi Luke,
Indeed, no solutions just by query parameters.
The right solution is either application side, or creating a second view for
this kind of query.


2009/4/30 Luke Randall <>

> Hi all
> I've got a an application tracking inventory movement. Each document
> contains a reference to the object, the month it occurred, and the
> number of units moved.
> What I'm now wanting to do is write a view to show the movement for a
> specified time frame, where the code looks like this:
> map: function(doc) {
>  if (doc['couchrest-type'] == 'Transaction') {
>      emit([doc['month'], doc['category']], (doc['amount']));
>  }
> }
> reduce: function(keys, values) {
>   return sum(values);
> }
> This returns items with keys like ['200904', 'Foo'], so I can specify
> date ranges (and optionally the object) for the view. However, I want
> the totals to be per object, not per object per month as they
> currently are.
> The obvious solution would be to use group_level=1, but I'm wanting to
> group by the second element in the key. I've also tried switching the
> order of the key's values, but I then lose the ability to specify the
> date range for the view, rendering it useless.
> Is there a way to either group by the second value of the key, or when
> passing start and end key values, to accept all given values in the
> first value of the key, but exclude them based on the second value.
> I've tried something like
> db.view('inventory/movement', :group => true, :startkey => [nil,
> '200904'], :endkey => [{}, '200905'])
> but it seems that if your have a catch all as your first value that it
> ignores the second value. I've looked around for any other discussion
> on this, but haven't found anything beyond what I've just mentioned.
> I'd be grateful if anyone can help with this, even if it's just to
> confirm that the only way to do it is to combine values at the
> application level.
> Thanks
> Luke

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