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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How to get all documents from a particular chunks in MongoDB?

From mongos log, I got the following message balancer move failed: { chunkTooBig: true, estimatedChunkSize: 408839903, ok: 0.0, errmsg: "chunk too big to move" } from: shard4 to: shard1 I know ...
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Mongo Memory mapping file size issue

I am witnessing some performance issues in my Mongo Sharded cluster. I checked the serverStatus for the memory uses on my shards This is the output Shard one Primary RAM size 512 GB "mem" : { ...
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after “mongod --remove” in Windows and then lost the databases

I removed MongoDB from the Windows Service by "mongod --remove" in command line and succeeded. After creating a new mongodb service with the same dbpath and "mongod --repair", I couldn't get the ...
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345 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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MongoDB GridFS delete operation too slow while mongod process takes up 100% CPU

I'm using Python (CPython 2.7.3 on Debian 7.8 amd64) with pymongo driver (version 2.7.2) to connect to a MongoDB (db version v2.4.12) database which has solely been used to store files in a GridFS ...
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278 views

Difference between mongod and mongodb upstart jobs

I just noticed that there are two possible ways to start mongodb: service mongodb start (uses /etc/mongod.conf) service mongod start (uses /etc/mongodb.conf) Can someone tell me what's the ...
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264 views

Issue while restarting - mongdb

I had tried to start the mongodb service using the following command in linux machine. service mongod restart I am getting the following error Stopping mongod: ...
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1answer
12 views

Setup MongoDB replica servers with different power?

Is it a good practice to setup replicas with the same machine size (wrt. CPUs, RAM, Bandwidth, etc.) or can replicas be based on smaller machines? One usecase might be to have a small non-voting ...
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90 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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40 views

Converting sql into mongodb nosql

I am trying to convert oracle sql into its mongodb equivalent version. create table my_hll as select mod(ora_hash(n), 1024) bucket, max(num_zeroes(trunc(ora_hash(n)/1024)))+1 val from previous_data ...
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668 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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27 views

Help - Error : Could not connect to master of shard replica set

I have a shard, using mongo v2.4.11. It has to mongos, 3 config, and 8 replica set (2 replica for each set, means 16 node for shard) It is keep having exception as per below. Caused by: ...
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245 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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25 views

What exactly should I backup in MongoDB when using replica sets?

I have several instances of MongoDB replica set servers with a primary and a failover machine for each replica set. The primary machine makes daily backups by creating an LVM snapshot and copying all ...
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83 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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107 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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3answers
728 views

Why is Mongo stuck in STARTUP2?

I have a Mongo replica set with a few secondaries. A box, which hosts a secondary instance, crashed and lost the database. I started the secondary Mongo instance again and now it's stuck in STARTUP2 ...
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1answer
15 views

Are my MongoDB servers right in setting?

I have a small web site, so I used two servers. A: master 4G Ram, 96G SSD B: slave 2G RAM, 96G SSD The B server is always for backup, no read, no write. In my application, many users can (and will) ...
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28 views

Failing to automatically re-connect to New PRIMARY after a replica set failover , from Mongoose (MongoDB, NodeJS Driver)

I made a simple NodeJS App, with Mongoose as MongoDB Driver. And connected to a mongodb replica set. The App is working fine until I shut down the current primary, When the PRIMARY is down, the ...
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29 views

Is there any way to change the size of preallocate data file in mongodb?

In mongodb data files are preallocates to a particular size,like first data file .0, the next .1, etc. The first file mongod allocates is 64 megabytes, the next 128 megabytes, and so on, up to 2 ...
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1answer
31 views

mongo: how should I layout my data

I have 2TB of data currently spread across many CSV files that looks like: { 'rec_date': "2010-01-29", 'rec_time': "09:15:00", 'site_no': '46', 'data_owner': '1', 'flow_period': '5', ...
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1answer
93 views

MongoDB syncingTo change

I have a 3 members replica set version 2.6.1 with following configuration "_id" : 0, "host" : "10.125.16.22:30000", "priority" : 2 ...
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2answers
29 views

Mongodb: Does not seem to respect capped size limit

Running mongodb on win2012 Mongo db version v2.6.4 Our collection is created with this param: capped:true, size:500000000000 // 500 gb But the data dir, that only holds this one collection, has ...
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44 views

Hierarchical data in MongoDB?

I have a question regarding Hierarchical data. Our app shows posts, that are structured inside parents. Here's how it goes: prof->sprof->subject->post (Each prof can contain multiple ...
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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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25 views

Issue with total count in sharded collection

I am having a collection which is sharded. This collection receives data from a script which is running hourly. On this data we do some aggregation. My issue when we insert data in collection and run ...
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60 views

Database structure for hierarchical quiz?

I'm doing a personal project where I have a quiz with a number of boolean questions. Each question will have a two answer choices "true" and "false". Based on the selected answer, a new question will ...
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1answer
26 views

mongoexport on 2.0.4

What I'm I missing here? I need data greater that ISODate("2015-01-11T00:39:40.121Z") I know many forums have different answers for the same issue. But non resolved. Need a different point of view ...
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96 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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54 views

Unable to start Mongodb. Appears to be crashed, if yes, how to recover my data

Below is the error when ouput when I am trying to start my local mongodb. I am unable to start it and after little exploration, I doubt my local db has been crashed. If yes, is there a way to recover ...
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103 views

Chunk Size is shown as 1 KB in mongo db logs even it is set to 300 MB

I am running a mongo cluster. Chunk size set is 300 MB but for today morning it is showing me in logs taht chunk size is 1024 Byte. I checked in current op there also it is showing chunks of 1024 ...
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193 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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1answer
200 views

Data Analysis with MongoDB or MySQL

I have a need for processing some data in order to come up with some statistic. This is the scenario: Each user can answer several questions from the question list. They pick their answers from a ...
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17 views

Config data base showing invalid date for collection modification sharding is stopped

For last few days my sharding is not working and every day i am seeing very slow writes. I tried to drop some existing data to create space. But while dropping some old data i got error and when i ...
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19 views

Repeat statement of ChunkManager: time to load chunks for empty

In my one of the MongoS server i am continuously getting the below chunkManager statement ChunkManager : time to load chunks for empty This is repeating in logs and the day it started insert in my ...
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1answer
113 views

Mongo DB Replica set Stuck at RECOVERING state

We have created a replica set and now the problem is 2 members of replica set [3 members set] are in recovering mode from 48 hours. Initially the size of recovering nodes was increasing and now even ...
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44 views

Can not drop db in sharded environment

I am trying to delete some old dbs in my sharded set up. Step i am taking are : Stop Balancer. Drop Db Start balancer But in some of the DBs i am getting these errors. "errmsg" : "exception: ...
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27 views

Old Mongos servers are found in config database mongo

For some time we are facing issue with our sharded set up as some times one collection randomly stuck on one shard. I have daily db (we create daily database with date) in my application where some ...
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30 views

Mongodb replication behind a gateway

I have a replicaset with 3 servers and I need to move two if them behind a gateway. The final setup would look something like this, Server 1 (PRIMARY) ________ | S | _____________ | _ _ _ _ _ _ _ ...
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1answer
67 views

Add new shard - always best?

In our setup, we currently have 3 shard set sharded cluster, each shard being a replica set of 3. Our writes are about to go up significantly to implement a new feature, and we know the extra data ...
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1answer
70 views

Mongo DB Backup & restore

0 down vote favorite I have a DB with 150GB of data. I am using the MongoDump and Mongorestore methods to backup and restore. My production server is running Mongo 2.2 and my test server is 2.6.1 ...
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1answer
339 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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269 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 ...
2
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1answer
38 views

MongoDB - real disk usage is LOWER than dbStats.storageFile

I'm a bit surprised by what I observe in my mongo server, so I would like to know if anybody understand how this is possible. I have one collection of around 15K documents. For each of them, I store ...
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27 views

Socket recv() timeout on slave node

Now I installed Mongodb 2.6.4 as master node. On another node I installed same version as slave node. I configure "only=xxx" parameter to sync xxx database. When I start up slave node.I get following ...
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91 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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1answer
52 views

Mongo db sharded “the collection's metadata lock is taken” issue coming very frequently

I am seeing this warning in mongoS log consistently for one collection. [conn96] warning: splitChunk failed - cmd: { splitChunk: "ibeat20150105.dgrpCount", keyPattern: { articleId: 1, host: 1 }, min: ...
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31 views

Mongodb instances and oplog

I would like to ask a couple of things about mongodb and replica sets: I have different meteor applications running on my private server; each one of them uses a different meteor database (and does ...
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35 views

Mongo Chunk 250000 document limit is creating problem in chunk migration

We can set chunk size limit for a DB. But chunk has a limit of 250000 documents per chunk. My chunk size is 250 MB which varies the number of document in each collections. So normally some of my ...
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319 views

What is lock pinger in mongodb

Can somebody explain me what is lock pinger in MongoDB [LockPinger] cluster XXXXXXX:27019 pinged successfully at Wed Feb 5 04:46:01 2014 by distributed lock pinger ...