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Subject: Re: reduce_overflow_error
From: J Chris Anderson <jchris@gmail.com>
In-Reply-To: <001AFFD2-5DCE-4E50-9F8B-37EF58C0C908@mymedify.com>
Date: Wed, 21 Jul 2010 21:10:41 -0700
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To: user@couchdb.apache.org


On Jul 21, 2010, at 4:59 PM, Talib Sharif wrote:

> Yup, thats what i discovered.
>=20
> Basically i had
>=20
> var val =3D parseInt(doc.field1.attr1)
> emit(doc._id, val)
>=20
> and doesnt necessaryily mean that it will will be 0 or something.
>=20
> i had to do
>=20
> var val =3D parseInt(doc.field1.attr1)
> if (val)
> 	emit(doc._id, val)
>=20
> Thanks,
> Talib
>=20

Also it is worth noting that equivalent to this reduce function:

function(ks, vs, rr) {
  return sum(vs);
}

is the plain text:

_sum

And it will be run in Erlang and be much much faster especially for =
group queries.

There is also _count if you would always be emitting the value 1 from =
your map and would like to count the # of rows. When you do this you can =
emit any old thing, and the value will be ignored, just the # of rows =
counted.

Chris


>=20
> On Jul 21, 2010, at 4:37 PM, J Chris Anderson wrote:
>=20
>>=20
>> On Jul 21, 2010, at 3:08 PM, Talib Sharif wrote:
>>=20
>>> I am getting the following error when requesting a view. My Db has =
about
>>> 100000 documents. And i have about 10 views with either having no =
reduce
>>> function or a reduce function with 'return sum(values)' as the =
return value.
>>>=20
>>> I tried the exact same views on a 2000 documents DB and i don't get =
this
>>> error. Am i hitting some wall in terms of size? Whats the best way =
to debug
>>> this?
>>>=20
>>> {"error":"reduce_overflow_error","reason":"Reduce output must shrink
>>> more rapidly: Current output: '
>>>=20
>>=20
>> Are the values scalar numbers before you sum them?
>>=20
>> You can run log(foo) to log to the couch.log from the view function.
>>=20
>> Chris
>>=20
>>>=20
>>> Thanks,
>>>=20
>>> Talib
>>=20
>=20