mapreduce with polymodel
We are thinking use mapreduce over a polymodel kind but is not possible filter only for subclass. what is the reason?

we are using model.get_by_key etc etc propertly. 

We can filter over mapper after fetch entity but we neeed iterarte over a lot entites for anything spending time and money.

any idea? how built my own DataInputEntityReader?
mapreduce with polymodel
===

We are thinking use mapreduce over a polymodel kind but is not possible filter only for subclass. what is the reason?

we are using model.get_by_key etc etc propertly. 

We can filter over mapper after fetch entity but we neeed iterarte over a lot entites for anything spending time and money.

any idea? how built my own DataInputEntityReader?