The map and reduce functions for Couchbase view to count the number of documents set to expire on a specific number of days from today by their key prefix with two levels.

CountTwoLevelReduce.js

function (keys, values, rereduce) {

  var result = {};
  if (rereduce) {
   	
    values.forEach(function (firstIndex) {
      for (var firstKey in firstIndex) {
        
        // try to get the result associated with this key
        var firstResult = result[firstKey];
        
        // when it doesn't exist then init default
        if (!firstResult) {
          firstResult = {};
          result[firstKey] = firstResult;
        }
        
        // get this result
        var secondIndex = firstIndex[firstKey];
        
        // merge all values
        for (var secondKey in secondIndex) {
          firstResult[secondKey] = (firstResult[secondKey] || 0) + secondIndex[secondKey];         
        }
      }
      
    });    
    
  } else {

    for (var i = 0; i < keys.length; i++) {
    
      var key = keys[i];
      var value = values[i];
      
      var firstResult = result[key];
      if (!firstResult) {
        firstResult = {};
        result[key] = firstResult;
      }
      
      var secondResult = firstResult[value];
      if (!secondResult) {
        firstResult[value] = 1;
      } else {
        firstResult[value] = secondResult + 1;
      }
      
    }
    
  }
  
  return result;
  
}

KeyPrefixTwoLevelExpiresInDaysMap.js

function (doc, meta) {

  var firstSeparator = meta.id.indexOf('_');
  var secondSeparator = meta.id.indexOf('_', firstSeparator+1);
  var separatorAt = Math.max(firstSeparator, secondSeparator);
  var keyPrefix = meta.id.substring(0, separatorAt);
  
  var expiresInDays;
  if (meta.expiration > 0) {
    expiresInDays = Math.round((meta.expiration - (new Date().getTime()/1000)) / 86400);
  } else {
    expiresInDays = -1;
  }
  
  emit(keyPrefix, expiresInDays);
  
}