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 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 ...
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2answers
65 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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2answers
956 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
491 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
80 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 ...
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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
303 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 ...
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1answer
613 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, ...
2
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1answer
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 ...
2
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1answer
601 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. ...
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1answer
134 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 ...
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1answer
517 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 ...
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2answers
372 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 ...
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 ...
2
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1answer
51 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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1answer
36 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 ...
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0answers
88 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 ...
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205 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 ...
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0answers
359 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 ...
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1answer
99 views

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 ...
2
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1answer
744 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. ...
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0answers
122 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
156 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 ...
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0answers
213 views

Store large hierarchy in NoSQL each day and compare

I'm in the process of creating a utility that stores a fairly large hierarchy into a NoSQL document. The data of this is similar to an Active Directory / LDAP structure which contains sub groupings, ...
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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
153 views

Does Mongo have disappearing/phantom writes

I have heard that Mongo has something like phantom writes. For example, if I have a web request with the following db commands in a single unit of work: a) update comments in article b) update ...
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0answers
136 views

automated data sync after Primary node is down

I have this scenario, using version 2.2.2: Node A, Primary, Priority: 10, Wireless network Node B, Secondary, Priority: 9, VM Server1 Node C, Secondary, Priority: 8, VM Server1 Sequence: In Node ...
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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 ...
2
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1answer
266 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
2k views

MongoDB - Should I separate the journal and the data to different drives?

I have seen and heard from multiple sources that it can be a good idea, performance-wise, to write your db journal and your data files to separate disks. What's the recommended way to do this (e.g. ...
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1answer
95 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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2answers
5k views

To find a version for your pc check with the software publisher install mongodb

I want to install MongoDb on windows 8 but when i try to run C:\mongodb\bin\mongod.exeiget this error: To find a version for your pc check with the software publisher.
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1answer
125 views

Where do caching servers conceptually fit in my architecture?

Given the simple well-known architecture below: Where (conceptually) does the caching server(s) sit?
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1answer
109 views

mongodb shard chunk migration 500GB takes 13 days - Is this slow or normal?

I have mongodb shard cluster, shard key is hashed. It has 2 shard replica sets. Each replica set has 2 machines. I did an experiment by adding another 2 shard replica sets, and it starts to ...
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1answer
43 views

What folders should I check to see if these MongoDB applications are installed on my server?

I have a CentOS (Linux) server and looked at the /bin directory, but don't find the applications listed below. What folders should I check to see if these applications are installed on my server? I'm ...
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1answer
106 views

Mongo db and sharding / replica sets concept questions

I have few questions about sharding and replica sets: I am planning to write important logs to a sharded environment. about 100 million rows in a day, If I will connect to a single MONGOS process , ...
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3answers
733 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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2answers
151 views

Does mongodb support non readable file?

I have uploaded PDF/PST file in mongodb by mongofiles but by retrieving them in R(BSON) and converting it to "Character" type i didnt find the PDF/PST file,so is it possible to upload PDF file or PST ...
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1answer
291 views

Books to start with big data [closed]

I would like to start learning about the big data technologies. I work in this area in the future. Does anyone know good books to start learning about it? Hadoop, HBase. Beginner - intermediate - ...
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1answer
911 views

$nearSphere returns too many data. What am I missing? Am I wrong? Is it a bug? Does other see the same thing?

I noticed that $near and $nearSphere returns completely different data and I got suspicious. After all, when latitude is near equator it sphere distance shouldn't differ a lot from euclidean distance. ...
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1answer
522 views

mongodb: replica-set processing reads on the primary

Running a replica-set with 1 primary and 2 secondaries, I wonder why the READs are also done on the primary. Shouldn't the primary mainly do the WRITEs and the secondary can share the READ-load?! I ...
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1answer
32 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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2answers
36 views

Separate login for user / administrators using mongodb

I have 2 separate groups of users on my website. One is user and the other one is admin. Currently I put them in 2 different collections user and admin and login respectively. My questions is: ...
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1answer
20 views

How to use fsyncLock() safely in backing up a single mongod

I read from mongodb document: important: db.fsyncLock() may block reads, including those necessary to verify authentication warning: When calling db.fsyncLock(), ensure that the connection is kept ...
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2answers
27 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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1answer
561 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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1answer
34 views

How to isolate 1 MongoDB config server

I need to preform a rolling upgrade on my MongoDB. I've been all over the Mongo documentation and I can't find a solution to my problem (if there is one) Here's a simple sketch of the Architecture: ...
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1answer
119 views

Update tag range on MongoDB range shard

Let say I set a min and max key for shards using range tags. Later I find out that the tag range I defined will not balance. Then I have to change the tag range value. I have searched MongoDB's ...
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1answer
227 views

MongoDB performance problem

I have a MongoDB for storing result like this {_id, type, imei, lat, lng, spd, dir, time} {_id, type, imei, lac, cid, time} If type is f first one is used and if it is l second one is used. Here ...
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1answer
78 views

Delayed replication false alerts and migration delays

I am running mongo 2.6.1 on a 3-shard cluster. Configuration is: 3 data nodes and 2 arbiters. The one data node is hidden and delayed for 3 hours (slavedelay). I have hidden the node in order to ...