couchdb-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jeff Hinrichs - DM&T" <je...@dundeemt.com>
Subject on emit...
Date Tue, 13 Jan 2009 13:07:48 GMT
I have a few questions on the emit function used in the javascript map
when building a view.  I'll start by explaining what I believe about
it.

The emit function returns 2 values, these values represent a
key/value (k/v) pair which are generated from the code in the map
function and the data in the document being processed.

w.r.t. emit(k,v)

If the view being generated is comprised of only  a map operation and
not a map/reduce operation, the (v)value part of this key/value
combination has no meaning as it is not used in the generation of the
view.?

In this scenario you should return a (v)value of Null.?

The (v)value returned affects the physical size of the view.?

The (v)value returned is not/can not be used when querying a map only view.?


Most examples I've seen show emit returning a simple scalar for the
emit'd (k)key, however I've also seen a list being returned.   When
would a list be preferable to a simple scalar?

Which articles on the web with regards to map/reduce would the dev
team encourage couchdb users to read?

Regards,

Jeff

Mime
View raw message