MongoDB is a scalable, high-performance, open source, document-oriented database. It supports a large number of languages and application development platforms. Questions about programming should be asked on http://stackoverflow.com.

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Mongodb replica sets: why does my master server occupy more disk space than my slave?

I have two servers on my replica set. Let's call it the master and the slave, for the purpose of this discussion. The master was the original one, and the slave was replicated from that master. At ...
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10 views

debian sudo service mongod status shows failed but mongo is working

I started a replica set with three servers with default port and used a different data directory. But when i did sudo service mongod stop. it said failed. so i went into mongo shell and did a shutdown ...
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21 views

MongoDB Insert Performance

I have some data which are aggregated in chunks and later pushed into another collection. The problem is that aggregated data pushing to another collection is very slow and takes from few hours and i ...
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285 views

exception: hosts cannot switch between localhost and hostname

I created a replication set. I added localhost in the set in the beginning, but when I try to edit the member with the actual hostname. I get error "exception: hosts cannot switch between localhost ...
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320 views

optimizing MySQL for traffic analytics system

background : I've developed a URL shortener system like Bitly with same features , so the system also tracks clickers info and represent as graphs to the person who has shorten the link as ...
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555 views

“ERROR: could not read from config file” MongoDB

I'm trying to configure MongoDB in OS X Mountain Lion. I've installed with Homebrew; I have followed lots of tutorials, but I have got an issue which I haven't been able to solved. The issue is about ...
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70 views

MongoDB - sharding

I have a sharded cluster with 4 shards, 3 config databases. My problem is when I do my inserts only one shard gets filled. Can anyone please explain to me why this is happening. My first thought was ...
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81 views

Selecting, filtering and aggregating in MongoDB

if we have two dataset 1-First dataset contains population data of cities in the United States of America. Each record in the dataset has the following format: { "city": "ACMAR", "loc": [ ...
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2answers
18 views

Query to Secondary on Sharded Cluster

How to specify query from mongos shell which is inteded to query data from secondary? The goal is not to bother primary load on write and use data in secondary shards instead.
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26 views

Repair database on Replica in sharded set up

I am using mongo sharding in my DB. The scenario I am facing is that I have deleted some of my collections in my DB. But as to reclaim the space I need to run repair option which i can not run using ...
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191 views

Mongodb ubuntu - config server and shard together

I have the following services on a single shard server: sudo mongod --dbpath /data/db/ --port 31001 sudo mongod --configsvr --dbpath /data/configdb/ --port 21001 The same server is using for shard ...
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13 views

MongoDB Tag-Aware Sharding Workflow

I wonder the work flow of sharding cluster in Tag-Aware Sharding. --- Sharding Status --- sharding version: { "_id" : 1, "version" : 3, "minCompatibleVersion" : 3, "currentVersion" ...
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21 views

Improve the insertion rate of mongo sharded cluster

I can't disable the write concern while i mongorestore with .bson file. It totally damages the insertion rate (insert/sec). This is my sharding status. mongos> sh.status() --- Sharding Status --- ...
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13 views

MongoDB - Change primary shard only for a certain database

I have a sharded MongoDB cluster running 3 different Databases. Currently all 3 databases has the same shard configured as their primary shard (shard000) Is it possible to change the primary shard for ...
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642 views

Storing multidimensional array in MongoDB

I am attempting to convert a large MySQL database of product information (dimensions, specifications, etc) to MongoDB for flexibility and to move away from the restriction of a column based table. I ...
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21 views

How to update a field in sharded environment in mongodb using C# driver

I have successfully done loading in sharded environment. It is working fine. But when I do update in sharded environment, I am getting the error as : WriteConcern detected an error 'update { q: { ...
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21 views

MongoDB - can read cause write locks?

I have a MongoDB database with ~100GB data size. I ran a test with 300 threads and a total 10,000 'read' queries. I notice on the MMS lock% it is showing 0.6 ~ 1% of write lock. My question is, the ...
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23 views

MongoDB - how to reduce numYields

I have a MongoDB database with ~100GB data size. I ran a test with 300 threads and queries are all reads, no writes (except writes to db profiler I guess). I enabled database profiler to keep track of ...
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14 views

MongoDB Manual References vs DBREF

I've been researching MongoDB and trying to see if it would be a fit for my company's product catalog. I came across database references: http://docs.mongodb.org/manual/reference/database-references/ ...
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30 views

Does remove document automatically remove the index that reference this document?

I am wondering if removing the document will automatically update the index if this document is referenced?
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13 views

Mongodb parent reference tree get current location and full path

I'm making parental reference tree with MongoDB and Mongoose. My schema looks like this var NodesSchema = new Schema({ _id: { type: ShortId, len: 7 }, name: { // name of ...
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2answers
26 views

MongoDB/MySQL - auto increment vs object ID

I am in the process of evaluating MongoDB and writing some basic PHP applications around it. Typically in my PHP/MySQL applications, I would create an ID field and set it to auto-increment on each row ...
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19 views

Do MongoDB's “read uncommit” and “write lock” conflict with each other?

I was reading the MongoDB documentation, where it says about read uncommit: MongoDB allows clients to read documents inserted or modified before it commits these modifications to disk, regardless of ...
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428 views

Write a query which add two fields of a document and compare their sum to third field in mongo

I have one document say db.pageTrendLog.findOne(); { "_id" : ObjectId("538b7128cf16e3ea5a1ab23c"), "pgDownloadTime" : NumberLong(9776), "pgAccessTime" : ...
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1answer
243 views

Best embed/reference/field strategy for many inserts (mongo)

I'm building a gaming backend with Mongo, and have some issues on how to best design the schema to maximize performance and database size. My models: User Match -ReferenceMany (User) ...
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2answers
45 views

One of databases in MongoDB suddenly gets high lock %

I observe repeatable, sudden, short-time update queries slowdowns in MongoDB cluster for single database. That slowdowns lasts about 30 seconds and repeats few times a day. I found that lock % and ...
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598 views

mongodb user for ubuntu EC2 instance

I am trying to install mongodb on Ubuntu EC2 instance. However, I am confused about what user the DB would run as: If I follow: http://docs.mongodb.org/manual/tutorial/install-mongodb-on-ubuntu/ ...
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86 views

Sample YAML Configuration Files for MongoDB?

The MongoDB configuration options documentation lists all the available options that can be specified, but does anyone have a set of fully formed example YAML formatted config files for MongoDB ...
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29 views

MongoDB Replica Set Can't be connected To

I just set up a replica set for a standalone Mongo instance using the following changes to my config and rs.initiate(). # in master/slave replicated mongo databases, specify here whether # this is a ...
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1answer
178 views

Mongo replication lag slowly increasing

I am running a replica-set in production with slaveOk = false using mongo 2.0.7 in AWS The replication lag on one of the servers is close to 58 hours. This replication lag is sometimes decreasing ( at ...
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40 views

MongoDB to store vehicle tracking information

I am building an app similar to Uber for tracking vehicles. Since the update frequency is so high (accounting for several users), I want to know the general practices involved for making writes faster ...
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1answer
78 views

Start mongod instance on replica set as background job

I have setup a Mongodb replica set with 1 secondary node. When i execute on secondary sudo mongod --replSet rs0 --dbpath /data --port 27017 --oplogSize 700 The primary and secondary nodes are ...
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1answer
18 views

Data distribution in mongos with shards or replica sets

I am a newbie to mongodb.I have set an mongodb architecture with a single mongo shard(mongos) connected to three shards(replica sets) with three config servers. The architecture looks as below: Now ...
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14 views

Standalone MongoDB to MongoDB Shard Setup

I'm learning MongoDB currently so maybe the title of this question is worded poorly, but I'm looking to understand the scaling of Mongo better. I did some research on what DB would be best for my ...
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693 views

mongodb 2.6 mongos start up failed

I'm trying to run mongodb 2.6, everything followed my 2.4 version setup steps. but when I start mongos I got the following problems and just cannot make it. 2014-04-24T03:38:31.001+0800 [mongosMain] ...
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2answers
3k views

Mongo replicated shard member not able to recover, stuck in STARTUP2 mode

I have following setup for a sharded replica set in Amazon VPC: mongo1: 8G RAM Duo core (Primary) mongo2: 8G RAM Duo core (Secondary) mongo3: 4G RAM (Arbiter) Mongo1 is the primary ...
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9 views

Proper tree NoSQL structure with focus on full-text searching

I developing an app with tree(folder-file) structure, on which I should perform full-text searches with MongoDB. I did a research on the best tree structure practices and found this great article, but ...
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17 views

Mongodb sharding balancing not working properly, says config servers differ [duplicate]

Iam using a mongodb sharding configuration in which there are 3 config servers, 2 query routers and 2 shards. One of my shard is having 32 gb data and other is having only 6 gb data. Balancing is not ...
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181 views

How can I use mongoDB efficiently in this scenario?

I'm trying to build a system of documents that have hundreds of tags assigned to them, but each document-tag association has a certain condition it has to also meet so the document would be returned: ...
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28 views

Migration of chunks not taking place in sharding

I am trying sharding in MongoDB. I am working with 1 config server 1 Query router 2 shards I tried hash based sharding. The data is getting partitioned but sharding is not successful. In one ...
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23 views

Can I copy a collection in mongoDB from one database to another by copying the db files directly?

I tried using cloneCollection http://docs.mongodb.org/manual/reference/command/cloneCollection/ , but clonecollection takes a lot of time in case of big collection because it starts indexing the data. ...
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201 views

How to setup a MongoDB replica set for the connector

I want to keep MongoDB and Solr in sync. The mongodb-connector (python) is the tool I want to use to do that. Now a replica set in mongodb is required (see ReadMe), but I don't want (and can) setup a ...
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1answer
58 views

Long running query on replica worker set in mongo

Hi I updated my mongo version from 2.4.to 2.6. Now when i see current op in mongos it shows me some queries which are running for long long time. one example is { "opid" : ...
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53 views

Problems in sharding in mongodb

I am currently working on sharding. I have certain issues related to sharding : 1.If I load data again to a collection which is already sharded, the data stays only in one shard and not migrating to ...
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1answer
319 views

Choosing shard key and friendly URL Ids for my MongoDB

I have decided to use MongoDB as my Database for a web application. However, I have some difficulties to get started and I hope that you can help me out with a few questions. I am developing my ...
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1answer
74 views

Use index intersection feature in mongo 2.6 to compound shard key

I am having three indexes like name,age,salary. I can use them as compound index as per 2.6 (name and age together). But can i use the same indexes as compound shard key like name and age. i also have ...
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10 views

MMS confusing between hosts in different replicasets

I see mms being confused between different hosts of replicasets, for example check the hosts below instead of mapping the hosts like vehicle-mongo-1.prod-3.cloud.edmunds.com ...
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23 views

Re-posting schema

I'm building a social network very similar to Twitter, in which users can see a feed with content posted by users they follow. Users can like and re-post (i.e. "Retweet") posts. Re-posted content ...
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52 views

MongoDB can't add new replica set member

I have a replica set, and I added a new member to the set. The initialSync begins for the new member and rs.status (on primary) shows STARTUP2 as status. However, after a long enough time, there's a ...
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11 views

MongoDB object pointing [migrated]

I am doing an web app and i have a doubt. I need to get a value of a MongoDb JSON? object. I post my code.. import pymongo try: conn =pymongo.MongoClient('localhost') print('Conexion ...