CouchDB reduce_overflow_error problem

map.js

function(doc) {
  if (doc.request_context.user_name
    && doc.timestamp
    && doc.day
    && doc.request_context.activity
    && typeof doc.request_context.activity !== "undefined") {
    var is_error = 0;
    if (typeof doc.response_status !== "undefined" && doc.response_status > 400) {
      is_error = 1;
    }
    out = {
      num_requests: 1,
      last_seen: doc.timestamp,
      days: {},
      activities: {},
      user_agents: {},
      num_errors: is_error
    };
    out.days[doc.day] = 1;
    out.activities[doc.request_context.activity] = 1;
    out.user_agents[doc.user_agent] = 1;
    emit(doc.request_context.user_name, out);
  }
}

reduce.js

function(keys, values) {
  var ret = {
    num_requests: 0,
    num_errors: 0,
    last_seen: 0,
    days: {},
    activities: {},
    user_agents: {}
   }
  values.forEach(function(val){
    ret.num_requests += val.num_requests;
    ret.last_seen = Math.max(ret.last_seen, val.last_seen);
    for (var key in val.activities) {
      if (typeof ret.activities[key] === "undefined") {
        ret.activities[key] = val.activities[key];
      } else {
        ret.activities[key] += val.activities[key];
      }
    }
    for (var key in val.days) {
      if (typeof ret.activities[key] === "undefined") {
        ret.days[key] = val.days[key];
      } else {
        ret.days[key] += val.days[key];
      }
    }
    for (var key in val.user_agents) {
      if (typeof ret.user_agents[key] === "undefined") {
        ret.user_agents[key] = val.user_agents[key];
      } else {
        ret.user_agents[key] += val.user_agents[key];
      }
    }
  });
  return ret;
}