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From Adam Kocoloski <kocol...@apache.org>
Subject Re: wiki edit on built-in reduce functions
Date Wed, 18 Jan 2012 02:21:46 GMT
On Jan 17, 2012, at 8:31 PM, James Marca wrote:

> Hi, 
> 
> this is a quick note for whomever is in charge of the wiki (my wiki
> account no longer has write ability)
> 
> Built-In_Reduce_Functions says that you need to emit numbers for the
> _sum operation.  As of 1.2.x, this can also be a list of numbers.
> 
> I just emitted a list of numbers and got what I expected...that is, a
> sum over each element of the list (not a summing up of the elements,
> summed.
> 
> Example:
> 
> no reducing, I emit a list of 4 items for each key:
> 
> ["2007-02-27", "1213122", "2007-02-27 14:46:00 UTC"]   [0.000007830687904038072, 0.000001032961291729275,0.0000012756780418961,
2.209310910297831e-7]
> ["2007-02-27", "1213122", "2007-02-27 14:46:30 UTC"]   [0.000008151766266816958, 0.000001042421330553939,0.000001315925015500657,
2.278253064474915e-7]
> 
> "Exact" reducing, same as emit with no reduce:
> 
> ["2007-02-27", "1213122", "2007-02-27 14:46:00 UTC"]   [0.000007830687904038072, 0.000001032961291729275,0.0000012756780418961,
2.209310910297831e-7]
> ["2007-02-27", "1213122", "2007-02-27 14:46:30 UTC"]   [0.000008151766266816958, 0.000001042421330553939,0.000001315925015500657,
2.278253064474915e-7]
> 
> level=1 reducing, summing up over each day
> 
> ["2007-02-27"]   [0.003547119931415267, 0.005496433891250249, 0.007064010452051014,0.003552803842322634]
> ["2007-02-28"]   [0.008437247339553495, 0.01664606221946668, 0.01779585111017863,0.01036210620457586]
> 
> 
> I observed this behavior in 1.2.x. I know this hasn't always been a
> feature, but I couldn't find whether it was 1.1 or 1.0, or what.
> 
> Regards, 
> James Marca

I believe it arrived in 1.1.0:

https://github.com/apache/couchdb/blob/1.1.0/CHANGES#L47

As far as the wiki goes, we needed to lock it down to deal with spam edits.  Happy to add
you to http://wiki.apache.org/couchdb/ContributorsGroup -- are you JamesMarca on MoinMoin?

Adam 
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