MongoDB : Calculating wrongly in mapReduce -


this collection named logins

db.logins.find().pretty()         "cust_id" : "testuser",        "created_at" : "2011-03-11 10:31:02.765"        "cust_id" : "testuser",       "created_at" : "2011-03-11 10:31:02.765"

i trying find out logins of each user based on date

i tried way 

var m = function() {     var aux = this.created_at.indexof(' ');     emit({cust:this.cust_id,daterr:this.created_at.substring(0,aux)},1); }  var r = function(k, values) {   var l = values.length;   var r = 0;   var i;   (i=0; i<l; i++) {     r+=l;   }   return r; }   q = function() {         var query = {"created_at": {$lt: "2013-04-30 11:19:52.587"}}         return query;     }  db.logins.mapreduce(m, r, { query : q(), out :  "userlogincountmonthly" });

i getting following output 

db.userlogincountmonthly.find().pretty()  { "_id" : { "cust" : "testuser", "daterr" : "2011-03-11" }, "value" : 4 }

what see value must 2 , shown 4

could please tell me why displaying wrong ??

i may totally off in since i've never used mongodb's mapreduce , i'm not quite sure you're trying achieve in reduce, looks wrong;

var l = values.length; var r = 0; var i; (i=0; i<l; i++) {   r+=l; } return r;

if values.length 2, loop twice, each time adding 2, returning 4.

as far can see since want count, simple return values.length make more sense reduce function.


Comments

Post a Comment

Popular posts from this blog

php - Why I am getting the Error "Commands out of sync; you can't run this command now" -

the documentation of error mentioned in title says if commands out of sync; can't run command now in client code, calling client functions in wrong order. this can happen, example, if using mysql_use_result() , try execute new query before have called mysql_free_result(). can happen if try execute 2 queries return data without calling mysql_use_result() or mysql_store_result() in between. from here: http://dev.mysql.com/doc/refman/5.0/en/commands-out-of-sync.html but in first query not fetching data mysql database, inserting. , in second query getting data database. here code $connection = mysqli_connect("localhost","username","password","tbl_msgs"); if(mysqli_connect_errno($connection)) { die("failed connect mysql: " . mysqli_connect_error()); } $query = "insert users (total_comments, total_views) values ({$total_comments}, {$total_views});"; $query .= "insert msgs (no...
Read more

ruby - Nesting modules inside of a Rails eninge gem -

what proper syntax nest child modules within parent module being isolate_namespace rails engine gem? # lib/myengine/engine.rb module myengine class engine < rails::engine isolate_namespace myengine # def ... end end for example. parent module myengine , child module blog. myengine share common domain, crud, taggable, searchable, etc, keep gem code dry , isolated main app (myapp), while inheriting isolated namespace , engine. are either of 2 approaches correct? refactor advice? # # lib/myengine/blog.rb module myengine module blog # def ... end end # b # lib/myengine/blog.rb module myengine class engine < rails::engine isolate_namespace myengine module blog # def ... end end end option a. correct, should lib/my_engine/blog.rb . can read more ruby & rails naming conventions here . further, if want put more modules or classes under blog namespace put them in folder lib/my_engine/blog , nest them under myengine::bl...
Read more

Eclipse formatter for java ending braces -

i know if it's possible setup eclipse format braces using banner style. we're working code uses banner style formatting , keep consistent within team version control reasons. here's example of banner style formatting not familiar: public class foo { //------------------------ public static void main (string[] args) { boolean condition = true; try { if (condition) { system.out.println ("condition true"); } else system.out.println ("not condition"); } catch (exception ex) { // handle errors } } //------------------------ } update: name style ratliff. experiment java->code style->formatter preferences. "banner style" seems poor use of space given outline view , quick outline functionality.
Read more