Ingo Radatz wrote:
Do you really want to eliminate keys? I would say you have to prevent the
uninteresting keys in the map step.
If you want to filter uninteresting values you have to return a filtered version of the
"values"-object in the reduce step.
I don't know the that the result is not interesting until the reduce has
been run so I can't filter during the emit. Let's say I have a set of
documents that emit:
[ a, v ] = 1
[ a, w ] = 1
[ a, x ] = 1
[ b, y ] = 1
[ b, z ] = 1
I understand that the result of the reduce for each unique key is stored
in index but this value could be re-reduce(reduce([ a, {v, w} ]),
reduce([ a, x])) and reduce([ b, {y,z} ]).
If the reduce function is a sum of the values when group_level=1 so it
would give:
[ a ] = 3
[ b ] = 2
but I only want results in the set when the final value of the reduce is
odd. Even when I don't know if it is the final reduce call I can
discard any intermediate points where the sum is even because even + odd
= odd. If I try to return null in the reduce/re-reduce when the value
is even I get:
[ a ] = 3
[ b ] = null
I would like to have just but I don't know (or if) the keys can be
entirely eliminated in the reduce step.
[ a ] = 3
Thanks,
James
