Hi Dylan This is what I'm trying to do: #groupby id and create 2 new columns: np2 and shared query = {'$group': {'_id': '$student_id', 'np2': {'$first': '$count'}, 'shared': {'$sum': 1}}}
The statement written above is one of the stages in a mongo aggregate query. The results of allthe stages are computed on the server side and the final result returned to the user. My problem is: I can't figure out 2 things: 1. How to add new columns while writing a Combiner/iterator 2. How to do group by (based on a condition since data in accumulo is always stored in a group). Best regards, Yamini Joshi On Sun, Sep 25, 2016 at 5:18 PM, Dylan Hutchison <dhutc...@cs.washington.edu > wrote: > Hi Yamini, > > Could you further describe the computation you have in mind, for those of > us not familiar with MongoDB's "Aggr" function? You may want to look at > Accumulo's built-in Combiner iterators > <https://accumulo.apache.org/1.8/accumulo_user_manual#_combiners>. They > seem more relevant than Filters. > > I don't know what you mean when you write that your output is not visible > to "the complete Database". > > Regards, Dylan > > On Sun, Sep 25, 2016 at 11:34 AM, Yamini Joshi <yamini.1...@gmail.com> > wrote: > >> >> Hello everyone >> >> I wanted to know if there is any equivalent of Mongo Aggr queries in >> Acuumulo. I have a complex query in form of a Mongo aggregate >> (multi-staged) query. I'm trying to model the same in Accumulo. As of know, >> with the limited knowledge that I have, I have created a class extending >> Filter class. My question is: since my queries depend on a input, is there >> any other way of using the iterators/filters only for one query or change >> their input with every single query? As of now, my filter is getting >> attached to the table on 'SCAN' that means the output will be visible to >> the subsequent queries and not the complete Database. >> >> Best regards, >> Yamini Joshi >> >> >