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: drop all collections

How to remove existing content before entering a replicaset the first time? mongodb worries about: ... has data already, cannot initiate set. All members except initiator must be empty.
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426 views

MongoDB does'nt starts after changing the data directory

I have installed a mongodb instance using yum..Now everything works fine.I started the service using service mongod start,it works good.Then i changed the data directory and log path in the ...
2
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1answer
1k views

how to upgrade the config servers to use WiredTiger in mongodb 3.0.0

I am reading the document upgrade config servers to use WiredTiger. In the section of "change config server to use WiredTiger", the second step is "stop the last config server listed in the mongos' ...
2
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1answer
129 views

Mongodb: too many namespaces raise on setProfiling

I have a mongodb database with a single (relatively big, around 130GB) collection, with 3 indexes, on which I'd like to do some profiling. However when I run the db.setProfilinStatus(1, 1000) command, ...
2
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198 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 ...
2
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663 views

MongoDB ReplicaSet reconfig when primary and majority don't exist

http://docs.mongodb.org/manual/tutorial/reconfigure-replica-set-with-unavailable-members/ Is there anyway to reconfigure a replica set in the event the primary as well as a majority of the servers ...
2
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1answer
306 views

mongodb: maxTimeMS ignored

After trying with different drivers and clients, we suffer with mongodb timeout on find query. Even Profiling logs the settings and issue well. 2014-08-13T23:46:43.218+0200 [conn80] query ...
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221 views

How do I add a user that has read access to only ONE database?

I have two databases admin and testdb ; Added a user Alice in the test database db.addUser( { user: "Alice",pwd: "Moon1234",roles: [ "readWrite" ] } ); But when I login using the user Alice, I can ...
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1k views

mongodb distinct() in an array

In my mongodb database,there is only one document below: { "_id" : ObjectId("5226efc5ccf23796f9590f67"), "count" : NumberLong(126045), "eissn" : "1466-5034", "grade" : 0.0, ...
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2answers
475 views

Can I run a mongos without any config servers?

I just want to use mongos as a tool to scale up the number of connections I can open to mongo. So can I run the mongos without any config servers? Has any one done this before?
2
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1answer
64 views

How to handle “or” possibilities in MongoDB

I'm new to MongoDB and by no means an expert in DB design in general. This feels like a really basic question that's probably been answered a million times, but I'm having a surprisingly hard time ...
2
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1answer
183 views

Which database to use? [closed]

Hey there. I am looking for a free to use for commercial website database that should have these design features, in the given order: Auto-Sharding (getting more free space by adding more server ...
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2answers
315 views

Sharded MongoDB backup solution

I am looking for a way that I can backup my 12 MongoDB shards into a single server. Disk space is not an issue but getting the backups to be on a single node would be the best. I am not sure if there ...
2
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2answers
920 views

mongodb service not running after changing path

I have changed the dbpath of mongodb.conf. And after that trying to start mongodb service,when I run sudo service mongodb start I get back mongodb start/running, process 7320 After that I run: ...
2
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1answer
394 views

Preserving whitespace in MongoDB values

In a simple scenario of me inserting a key-value pair, when value contains some white space, how can I preserve it? Example: > > db.bar.insert({"name":"mike "}) > > db.bar.find() { ...
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2k views

Storing dictionaries in mongo

Is there any reliable and fast database architecture that allows to store a dictionary(containing up to hundred thousand words) using mongodb?
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2answers
3k views

How to display query result in rockmongo by using execute method

I executed a command in mongo.exe > db.tablebusiness.find({"_id": "the-simmons-paradise__41.85_-87.88"}); I got results: Now I try similar command in rockmongo. If I execute ...
2
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1answer
67 views

Mongodb high lock percentage / slow queries

I'm working with an application using MongoDB that is getting a fairly large number of incoming requests and I've noticed that the responses are getting slower as the number of requests get higher. ...
2
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2answers
228 views

Mongos version 3.0.1 Split Chunk Error with Sharding

I have 3 config server and two shards. Each shard has a primary, secondary and an arbiter. This is running with the following mongod settings: storageEngine=wiredTiger ...
2
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1answer
521 views

When upgrading config servers to use WireTiger, the running config server with wiredtiger does not authenticate the existing pass and user?

In order to upgrade mongodb to 3.0.0, I am upgrading my config servers to use WireTiger. I followed the subsection of Change Config Server to Use WiredTiger. There are 18 steps. I run mongodump --port ...
2
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1answer
78 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 ...
2
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1answer
79 views

Mongodump on Replica Set

Running backups on a Mongo Replica set - 1 primary, 1 secondary, 1 arbitrar. Had a instance where all three stopped talking to one another and all went to secondary. I ran a backup against the the ...
2
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2answers
107 views

MongoDB replica sets and data duplication

I am new to MongoDB and trying to understand replica sets. Specifically, I am trying to understand how MongoDB would handle the following situation: A record is written to a table with a unique ...
2
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1answer
1k 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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2answers
2k views

MongoDB YAML file problems on Windows

I managed to get MongoDB running as a three member replica on Windows 8, but I had problems with configuration files. If I used the new (MongoDB 2.6) file format (YAML) and used the replica set name ...
2
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1answer
1k views

MongoDB - Query elemMatch Date

Having a document structure like this: { "_id" : ObjectId("5359816b036493327d7cae95"), "_class" : "com.myproject.MyObjectDTO", "signals" : [ { "signalType" : "ABC", "quantity" : ...
2
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1answer
202 views

What are these files in MongoDB?

I was looking into my server and I found this: [root@host ~]# cd /var/lib/mongo/journal/ [root@host journal]# ls -lh total 3.1G -rw-------. 1 mongod mongod 1.0G Apr 7 01:18 j._0 -rw-------. 1 mongod ...
2
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1answer
660 views

SpringData MongoDB - infinite getmore on mongo logs

Doing 2 queries on MongoDB through Spring Data on around 160 000 rows, query 1 is executed in few seconds (about 20 results) but query 2 never finish. I'm getting this line over and over on mongodb ...
2
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1answer
754 views

Mongodb 2.6 Server crash and not restarting

We are using mongodb 2.6 with one Primary and 2 secondaries. One of the secondary has gone bad and not restarting. 2014-04-18T21:13:34.765+0000 [rsSync] replSet still syncing, not yet to minValid ...
2
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1answer
1k views

Can't take a write lock while out of disk space

Help me please! My C:\mongodb-win32-x86_64-2.4.6\data size is 8G. I have 95G free space of drive C. But I get this message: com.mongodb.WriteConcernException: { "serverUsed" : "/127.0.0.1:27017" ...
2
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1answer
452 views

Can arbiterOnly replica in MongoDB become SECONDARY and what it means?

The MongoDB documentation says that when a replica is added to the set as arbiterOnly=true it will not become Primary. But can Arbiter become a secondary and what does it when it does? I have a ...
2
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1answer
3k views

How to create an efficient, scalable, multi-tenant data layer using MongoDB? [closed]

I'm working on the architecture for my upcoming Project Mangement app (as an example) and I'm seeking clarity on how best to design the MongoDB data layer, with specific regard to multi-tenancy. The ...
2
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1answer
109 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 ...
2
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1answer
808 views

How much free space do I need for mongoDB? and how to reclaim lost space?

I ran out of disk space on my mongo database. I saw it and dropped some collections (120 out of 1700 i had). And ran db.compact(...) thinking it would release free space. well, that was a stupid idea. ...
2
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1answer
156 views

Improving concurrency in MongoDB via sharding

Our current setup: Cluster of ~500 ec2 c1.xLarge worker nodes with 8 threads on each running scientific simulations Results temporarily stored at runtime on each worker node's local MongoDB, using ...
2
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1answer
786 views

MongoDB: move documents before capping

The cappedCollection concept works well for most of my projects where cleaning old data without care makes sense. For another projects, I need a more complex and safe concept. The requirement is ...
2
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1answer
348 views

MongoDB: Aggregation workaround by helper collection

Since I regularly run against mongodb's document size limit and also aggregation framework's group limitations >16M, depending on the amount of data I need to process, I look for a simple workaround. ...
2
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2answers
427 views

Schema design for privacy settings in MongoDB

I have a set of documents that can have various privacy settings around them: They can be completed public (any registered user) can view them They can be viewable only by people following you (this ...
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0answers
22 views

Why is our Non-Mapped Virtual memory usage high when running MongoDB (MMAP) on CENTOS

Our non-virtual virtual memory usage on our Linux MongoDb instances seems high, currently sitting just over 2GB. The instances are running a minimal installation of CENTOS (no GUI) and they acting as ...
2
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1answer
205 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 ...
2
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1answer
171 views

mongoexport not exporting all possible data

I have a collection with documents similar to the following: { _id: 'p_123456', id: 123456, kind: 'person' data: [...] } id field can contain either positive or negative integers. This ...
2
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0answers
176 views

Error while creating an admin user in replica set

I have a relatively simple replica set test setup between two VMs and my host machine, with VM1 as primary, VM2 as secondary and the host as arbiter. I have mongodb 2.6.4 installed on all machines. So ...
2
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1answer
420 views

MongoDB Replica Set: Can't Add Member/Connect

I'm building a MongoDB replicaset w/ three Ubuntu 14 servers. I'm connected to the primary server and authenticated w/ userAdminAnyDatabase and clusterAdmin privileges. When I run ...
2
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0answers
335 views

Mongo not using enough RAM, and is slow

Our Production Mongo appears to be behaving weirdly. As far as I have read, Mongo should eat up all the available RAM to cache Index and Data in memory but in our case it is not doing so. Our ...
2
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0answers
719 views

“Host has low open file limits” error in MMS

I am running Standalone MongoDB (v 2.6.0 64-bit) host on Centos (v 6.5). Centos is guest OS on Windows 7 host running under VirtualBox (4.3.10). MongoDB process runs under root account. And it is ...
2
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1answer
435 views

Best design of mongo replica set for DB read/write speed

I'm building a Node app that uses MongoDB. Whilst it would probably be fine to have node and mongo sitting on the same VPS, I want to ensure that the MongoDB is backed up and maintain high ...
2
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1answer
3k views

MongoVUE connect to mongodb with authencation failed!

I had a mongodb ,and a database named genbank ,genbank has a user whose role is "read" and "readAnyDatabase",it is very strange that I cannot connect genbank through this role by MongoVUE ,but I can ...
2
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1answer
1k views

verify that mongos server is connected to config servers

I've been writing a backup script for sharded replica-sets and it's almost done, except that I can't seem to get it to successfully start the balancer back up after everything's all said and done. ...
2
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0answers
138 views

MongoDB advantages [closed]

I am actually can not understand the real advatage or killer feature of MongoDB storage. As I understand currently MongoDB implements exclusive per-database write lock that is even worse from the ...
2
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1answer
185 views

Memory management scenario with MongoDB

I'm implementing a medium scale marketing e-commerce affiliation site, which has following estimates, Total Size of Data: 5 - 10 GB Indexes on Data: 1 GB approx (which I wanted to be in memory) Disk ...