Questions tagged [mongodb]

All versions of MongoDB - a scalable, high-performance, open source, document-oriented database.

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1answer
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MongoDB Keys and casting between types

This is more of a theoretical question: Let's say I have a collection of documents, my_collection: { "_id": ObjectId("52c679ac7a23e6225b62c51f"), "date": ISODate("2014-01-06T03:48:30.737Z") }...
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1answer
81 views

why should use MongoDB [closed]

In which types of projects, MongoDB is the best suited? Can we use MongoDB in large applications? Why Open Source CMS and framework doesn't have support for MongoDB? How it is different than other ...
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3answers
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MongoDB doesnt start normally?

I want to start mongo on terminal but it gives connection error like: MongoDB shell version: 2.4.5 connecting to: test Sat Jan 4 10:18:16.779 JavaScript execution failed: Error: couldn't connect to ...
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1answer
3k views

How does MongoDB store data in RAM?

I'm trying to sift through the remains of an event that was causing us a lot troubles. Aside from report to management about what happened, I'm trying to gain a much better understanding of how this ...
2
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0answers
150 views

mysql vs mongodb cache/load balancing

I have a system where users can 'like' content. There will likely be many hundreds of these likes going on at once. I'd like it to be AJAX driven so you get an immediate response. At the moment I ...
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1answer
758 views

High Global Lock % on Mongodb

I've just started using Mongodb v2.4.8 and the global lock % averages 80% which seems rather high to me. The CPU usage is around 120% on a 2 core, 2GB RAM, SSD VPS running Ubuntu 12.04 64bit. iotop ...
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2answers
573 views

What database should I use to create a webmail service like gmail? [closed]

I planned to use python for my frontend with django framework. But for backend, I have no idea which database I should use. Since it involves plenty of reads and writes can someone point me in the ...
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2answers
2k 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?
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1answer
580 views

How to manage users and collections in MongoDB? [duplicate]

Im triying to create users in a database in mongo, I want to lock the usage of te collections for some users, I'll give an example: Lets say that I actually have a db with 3 collections: Books, ...
2
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1answer
2k views

Should I save “document ID” as a String or Number in MongoDB

So I'm importing about a 100,000 documents into mondoDB. MongoDB already generates an Object hash but the data has a documentID that was used to identify records in the previous database. The IDs ...
1
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1answer
619 views

Permission error replica set

I'm having some trouble with intentionally removing a secondary from a replica set. I'm trying to simulate unexpected shutdown. My replica set consists of one primary and 2 secondaries. When I shut ...
2
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1answer
479 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 linked ...
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1answer
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Where to insert data after sharding?

Actual database in localhost:30000 ------------- I used this as Shard1 another mongod in localhost:30001 ------------- Shard2 another mongod in localhost:30002 ------------- Shard3 Added 1 ...
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2answers
5k views

Should I index before or after importing a dump?

I am using mongodb to persist a very big-size (90G), which has nearly 40,000,000 items. I read and parse this file and insert all items into mongodb (my programming language is perl, batch_insert, and ...
1
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1answer
276 views

Shard key selection for both write scaling and query isolation?

From the mongod documentation, I know that when choosing shard keys the key should always have high cardinality, so write operations are distributed to different shards (a kind of write scaling). But ...
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4answers
25k views

How to connect to MongoDB on Windows 8

I'm trying to get MongoDB installed and running on my new Windows 8 computer. However, I cannot seem to be able to connect to MongoDB when using the mongo.exe shell. I got the following error: ...
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2answers
3k 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
201 views

how to start sharding in mongodb

I am trying to learn sharding in MongoDb and here is my plan: I'm trying to shard the database S001 into 2 different machines. 192.xx.xx.60>mongod -configsvr --dbpath S001 ..Now running in ...
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2answers
49 views

Can sharding work with replication?

Basically we need to have a replication, a minimal setup. Primary - Slave 1 - Slave 2 Is it possible in the future we Shared it? What would be the setup? Is it going to have shared on Slaves like ...
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1answer
425 views

Shard keys must all be ascending?

I have a collection that I've been trying to shard, but I can't get it to shard with the index that I gave it. The collection in question uses a hashed index, which I created using: db.bar....
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1answer
129 views

MySQL geospatial query optimisation suggestions

I am new to DB Administration. Trying to sort out this query which is the heart of our application. I am searching google on similar questions, but would like an experts opinion on my particular ...
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1answer
709 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 ...
2
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1answer
1k views

Set replica set member host names on Secondary

I have a replica set rset1 that consists of a primary, secondary, and a backup server. I recently just changed their DNS names in Route53--the only name that didn't change was the Primary's, ...
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1answer
657 views

Would you use MongoDB in high-transaction environment? [closed]

using other words: does the one-write-lock-per-database policy (it's not a "bug" but a "feature" by design) affect contention making its usage in certain kind of workloads less then optimal? if not ...
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2answers
3k views

Mongodb restrict access on collections level

I'm building a backend system using MongoDB. Now I want to restrict access on certain numbers of database collections to this system. For example I have users, admin_users, pageviews and I want this ...
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2answers
2k 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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0answers
682 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. ...
3
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2answers
4k 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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2answers
1k views

How secure is mongodb with elastic beanstalk and EC2

I have a questions. I run MongoDB on one of instances of EC2 and application on Elastic BeansTalk. I restricted access to DB: only application can access it. DB instance has Elastic IP because it is ...
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4answers
63k views

Difference between Sharding And Replication on MongoDB

I am just confuse about the Sharding and Replication that how they works..According to Definition Replication: A replica set in MongoDB is a group of mongod processes that maintain the same data ...
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2answers
1k views

Running a simple logging program, how to diagnose spikes mongod's CPU activity?

I'm running mongodb 1.4.7 - I've a node server set up which logs incoming requests in a logs collection: {'u':'user123', 'l':'log data'} In addition, once the request happens, the server will check ...
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1answer
60 views

Replicating MongoDB server on windows

I have a main server(windows-27017) and on that i replicated my data on different port (37017) but same server. Now i am trying to add my notebook as a replicate server on mongodb and installed ...
0
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1answer
473 views

MongoDB Storage Architecture (MySQL innodb_file_per_table equivalent to MongoDB)

I am new to MongoDB.I looked inside dbpath I found users.0 - 16.8MB users.1 - 33.6MB users.ns - 16.8MB Further when I dig deeper I found, The .0, .1 files are datafiles. Each datafile is ...
4
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2answers
8k views

How to Determine Chunk Distribution (data and number of docs) in a Sharded MongoDB Cluster?

Having done all the right things - picked an appropriate shard key, scaled horizontally, distributed my data across several shards, I find I now have no real way to determine how well balanced the ...
0
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1answer
1k views

MongoDB shell version error (Server has startup warnings)

I installed MongoDB under Ubuntu server and when inter to MongoDB shell i got this error and warnings. MongoDB shell version: 2.4.7 connecting to: test Server has startup warnings: Sun Oct 27 09:58:...
2
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1answer
328 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
6k 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 ...
0
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1answer
631 views

Launchctl in 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 ...
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0answers
2k views

Installing mongodb as service

I'm trying to install mongodb as service on a machine running Windows Server 2008R2. I'm getting this message in the command prompt: The service is not responding to the control function. More help ...
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2answers
7k views

Diffrence between relational and unrelational database [closed]

What is the difference between relational(MySql) and unrelational database(MongoDb)
0
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1answer
633 views

Multiple system.replset collections in local

I have a replicaset that's showing multiple system.replset collection in the local db. replset1:PRIMARY> show collections; me oplog.rs replset.minvalid slaves system.indexes system.profile system....
0
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1answer
233 views

MongoDB cloneCollection between CentOS servers times out at 2 hours

I'm trying to clone a MongoDB collection from CentOS server A to CentOS server B. Both are running 2.4.6. The copy works great until exaxctly 2 hours, at which point I get a 9001 socket exception: "...
2
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2answers
502 views

MongoDB scaling when working with files

I have read through the MongoDB manual about sharding and replicasets. However, I would like to know if the following can be achieved with sufficient performance (read/write): Saving 10,000,000 ...
0
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1answer
219 views

What does maintenanceMode -7 mean on a mongo primary?

I've recently promoted a new member to primary of a mongo replicaset. Things seem to be running smoothly for several days and am not seeing any application symptoms of any problems. However peeking ...
2
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1answer
2k views

Need a solution to store cheaply a big MongoDB collection

We have the typical problem of Twitter's timeline tweets, or Facebook profile's news: we need to show the users only the new information (storing them in a fast db), and put all the old ones somewhere ...
1
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1answer
984 views

Based on what criteria voting take place in MongoDB?

Suppose a replication set R1 contains one primary, 2 secondary and one arbiter node. Voting will happen if the primery node goes down. Based on what criteria secondary members will vote to select the ...
4
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3answers
11k views

Write Locks in Mongo DB

I read somewhere that MongoDB holds db level write lock, does this mean that when someone updates any collection others are not allowed to read other collection or how it works. Also when someone ...
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1answer
1k views

I found the normal ULimit setting for mongo db is as follows:

I found the normal ULimit setting for mongo db is as follows: -f (file size): unlimited -t (cpu time): unlimited -v (virtual memory): unlimited [1] -n (open files): 64000 -m (...
3
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1answer
372 views

Accessing unsharded database in a MongoDB shard cluster without going through mongos?

As far as I can understand, not all databases in a MongoDB shard cluster have to be sharded; I can keep some databases unsharded, on only one of the shards. So suppose I have a shard cluster, with ...
6
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1answer
5k views

Can I disable journalling to improve performance

We have a 16 shard MongoDB 2.4 installation running in AWS that is eating money. The data is volatile, it only gets used within 15 minutes of creation If the cluster goes down we wipe it out and ...