couchdb-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Seggy Umboh <seggy.um...@gmail.com>
Subject Re: Slow Map Reduce
Date Sat, 24 Oct 2009 09:55:06 GMT
Thanks for the prod! I've added it to the bottom of this page as Map/Reduce
debugging:

http://wiki.apache.org/couchdb/Troubleshooting


On Fri, Oct 23, 2009 at 5:37 PM, Chris Anderson <jchris@apache.org> wrote:

> On Fri, Oct 23, 2009 at 5:00 PM, Seggy Umboh <seggy.umboh@gmail.com>
> wrote:
> > One thing I have found useful is to fire up js on the command line and
> just
> > assign a sample document to the variable doc, then run the map function
> on
> > that.
>
> Sounds cool, if you put together a blog post on the technique I bet
> people (including me) would read it.
>
> >
> > On Fri, Oct 23, 2009 at 4:18 AM, Rajkumar S <rajkumars@gmail.com> wrote:
> >
> >> Hi,
> >>
> >> Thanks, I had caught this bug and fixed it in the map, but did not
> >> update the mail. I just wanted the sum. but right now I am not using a
> >> reduce function just a map. Even for that I am not getting a result.
> >>
> >> Any way I am just learning the ropes so might take some  time before I
> >> figure out the stuff :)
> >>
> >> raj
> >>
> >> On Fri, Oct 23, 2009 at 6:40 AM, Seggy Umboh <seggy.umboh@gmail.com>
> >> wrote:
> >> > It looks like you just want to find out how many rows were emitted?
> That
> >> > would just be the typical sum right?
> >> > return sum(values);
> >> >
> >> >
> >> >
> >> > js> var v = 6
> >> > js> 0 + v.length
> >> > NaN
> >> >
> >> >
> >> >
> >> > On Wed, Oct 21, 2009 at 11:45 PM, Rajkumar S <rajkumars@gmail.com>
> >> wrote:
> >> >
> >> >> On Wed, Oct 21, 2009 at 9:48 PM, Paul Joseph Davis
> >> >> <paul.joseph.davis@gmail.com> wrote:
> >> >> > I suspect "return values;" is the culprit here. That's pretty
much
> >> >> guranteed
> >> >> > to cause you problems as the data grows recursing up the tree.
> 0.10.0
> >> >> even
> >> >> > detects this and throws an error to avoid precisely this issue.
> >> >> >
> >> >> > It's been discussed a couple times on the list but my stomach
is
> >> >> rumbling.
> >> >>
> >> >> That reduce function used in that log was the following.
> >> >>
> >> >> function(keys, values, rereduce)
> >> >> {
> >> >>    length = 0;
> >> >>    if (rereduce){
> >> >>        for(var v = 0; v < values.length; v++){
> >> >>            length = length + v.length;
> >> >>        }
> >> >>    } else {
> >> >>        length = values.length;
> >> >>    }
> >> >>    return length;
> >> >> }
> >> >>
> >> >> The reduce function should returns a single integer and not cause
> data
> >> >> to grow. Let me try with simpler map with no reduce and will report
> >> >> the results.
> >> >>
> >> >> with regards,
> >> >> raj
> >> >>
> >> >
> >>
> >
>
>
>
> --
> Chris Anderson
> http://jchrisa.net
> http://couch.io
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message