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

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188 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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8 views

Cannot Start MongoDB

I cannot start MongoDB on Debian(Jessie 8.4 Stable). I generated the keyfile and added the path to the key file to the configuration and uncommented the "auth=true" but when I try to start the service ...
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181 views

How to setup sync between MongoDB and C# .NET Application

What is the best practice to synchronize a MongoDB remote database with a C# .NET App that would allow queries to be responded to within the local file system and update itself when there is a change ...
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78 views

How come MongoDB WiredTiger snappy & zlip compression consumes same memory

To specify compression for specific collections, you’ll need to override the defaults by passing the appropriate options in the db.createCollection() command. For example, to create a collection ...
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4 views

How to show all users of all databases in mongodb?

I know show users or db.getUsers() can show all users in current database in mongodb, but how to list all users in all databses for ease of management as an administrator?
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142 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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715 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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1answer
21 views

MongoDB start ID and end ID

I want to insert bulk data into a MongoDB. Later on I want to find exactly the bulk I inserted. In MySQL I would have done: SELECT * FROM data WHERE id >= start_id AND id <= end_id How can ...
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1answer
433 views

what is the password to user mongodb when mongodb is installed in ubuntu?

When I installed mongodb in ubuntu, user mongodb and group mongodb are created in /etc/passwd and /etc/group. But I have no idea of the password to these user and group. I have to run mongod as root ...
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15 views

MongoDB script to backup replication set locally to a ubuntu 14.04 server

I would like to make a Daily Backup of my MongoDB from a replication set running from ubuntu 14.04 server. End goal would be to get a daily backup and write the backup to a remote or local share - ...
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8 views

how to get recordStats in mongodb 3.2?

I want to monitor accessNotInMemory of mongodb, before I can use db.adminCommand({'serverStatus': 1})['recordStats'] but according to mongodb doc, Changed in version 3.0: serverStatus no ...
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23 views

How to set a mongodb node to return as the primary of a replication set?

There is this question here: How to force a mongod to become primary in a replica set? But it was not the answer I was looking for. and there is the question below, which could be related but it is ...
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28 views

Want To Learn About MongoDB [on hold]

I am doing a little bit of research on MongoDB related to the following key points: (i) Experiment And Results (In which applications, MongoDB is used and what are the results) (ii) Threat To ...
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1answer
74 views

Improving mongodb read throughput for tiny database

I am given to understand that MongoDB will essentially perform like it is pulling records from memory if the working set is small. I wrote a simple MongoDB test program that inserts just one record ...
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1answer
73 views

mongodb could not find host matching read preference { mode: \“primary\” } for set?

I am deploy a monodb sharding, I have deploy a replica set in three machines: dev41:27017,dev42:27017,dev193:27017 and configsvr in three machine: dev41:27019,dev42:27019,dev193:27019 and also a ...
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345 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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6 views

MongoDB: what is the better way to implement shared record with ability to remove it by each user

I have a MongoDB record, for example, called Letter. This letter can be sent to some group of users, so many users have an access to it. A Letter can be sent in a context of Topic that is shared ...
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11 views

Data Modelling of product and product variations

I want to model product and product variations using mongodb (mongoose) I am really confused with how shall I model both I need to add stock and price to variations. Variation can be of anything (not ...
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13 views

Is there a way to find out if value exists with addToSet?

addToSet adds values to an array if the value doesn't exist. If the value already exists MongoDB will not return anything saying that it exsits. Is there a way to find out if the value exists? ...
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20 views

Solr with SQL Server or NoSQL

I am working on a POC of using Solr with SQL Server. I have a very complex data model with SQL server which required a bunch of joining and scalar functions to strip some mark up and other stuff. ...
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1answer
3k 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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2answers
772 views

MongoDB: Server sockets closed after a few minutes

I am working with multiple AWS intances connected to the same mongo database (inside Compose.io Elastic deployment) but I keep getting the error server <url>:<port> sockets closed after a ...
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1answer
99 views

Mongodb background indexing - no progress

I have added a couple of background indexes on few collections on mongodb replicaset (3.0.2, MMAPv1 storage), and since then I'm seeing following entry in db.currentOp(true) response in all nodes ...
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14 views

Getting empty folder when using mongodump to back up my MongoDB

Basically, I have a problem with using mongodump to back up my MongoDB. This is the general syntax I use in SSH: mongodump -d myDatabaseName -o ~/backups/my_backup This is the resulting message: ...
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7k views

MongoDB doesn't start 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 well. Then I changed the data directory and log path in the ...
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1answer
114 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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1k views

MongoDB all replica set members are “OTHER”?

I am setting up a MongoDB replica set using EC2's image: https://aws.amazon.com/marketplace/pp/B00CO7AVMY/ref=dtl_recsim_B007IBMJPI_B00CO7AVMY_3 MongoDB version 2.6.5 I have managed to set up ...
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377 views

How to access the data of collections from the .ns and other core storage files in mongodb?

My database in MongoDB was not accessible after the journal file became of the size > 1 GB . So I restarted the mongod process with a different data path to store the mongodb files in my machine. Now ...
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15 views

MongoDB collStats.size compared to collection.totalSize

I have a collection which has the following dimensions: rs0:PRIMARY> db.myCollection.totalSize() 2188206080 rs0:PRIMARY> db.myCollection.stats() { "size" : 5899660704, "avgObjSize" : ...
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2answers
473 views

Locked out of my own database through invariant() failure

I am trying to set up mongodb on my own server and connect to it remotely through my laptop. I had successfully installed the database and created my own user with admin privileges. However, when I ...
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2 views

Can't stop MongoDB process on CentOS

My OS is CentOS release 6.4 (Final) and my MongoDB version is 2.4.1. I tried: use admin; db.shutdownServer() and I got in output: assert failed : unexpected error: "shutdownServer failed: ...
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138 views

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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101 views

Why sharding does not show any improvement?

Here is what I did to test sharding performance. I have 4 servers, I ran config server and router on a server. 3 others are meant to be shards. First, I only added one shard to router, then I ran a ...
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19 views

Adding secondary via rs.add on MongoDB

I have a master and slave on linux (centOS 7). The rs.initiate(cfg) was done but its shows the below output when trying to add secondary via rs.add. I get this: How do I resolve? Version: The ...
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1answer
145 views

MongoDB: Should I combine fields for performance in limited circumstances

I have a really simple MongoDB collection: { "user": 1, "domain": "example.com", "apiAccess": true } There's an index on the "user" and "domain" fields. I always perform the same type of ...
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19 views

MongoDB Single Array or Multiple Fields

I have a MongoDB for a game, and I made a collection to store all outgoing attacks. My question is which of these models is more efficient. spearMenCount: type: Number required: true ...
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2answers
5k 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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1answer
2k 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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15 views

Speeding up MongoBD query { $ne: [] }

I'm currently doing a MongoDB aggregation but then have a query looking for all documents where a certain field, whose value is an array, is empty. obs = db.collection.count({'things.titles': ...
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192 views

MongoDB to MySQL Replication Automatically

i have Mongodb server and mysql server. i want to use mongodb for "write" and mysql for "read". so i am looking for some tool or some process by which we can tranfer mongodb to mysql server on ...
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18 views

Is it possible which documents couldn't be dumped using “mongodump”?

I am removing historical data from a collection in MongoDB (3.2), but first I need a backup of it. The choice has fallen, a simple combination of: mongodump --db myDatabase --collection myCollection ...
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12 views

Running a query in Mongo Shell vs PyMongo (in Flask) results in extreme slowdown

When prototyping a query I've been using just the Mongo Shell to make sure my aggregation query is working fine: # Default query query = [{ # Supposedly forces MongoDB to initially use ...
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1answer
22 views

How to get mongdodump --quiet to still report errors?

I'd like to run mongodump so that it only outputs errors (to avoid extraneous logwatch reporting for an automated nightly backup script). I've tried mongodump --quiet but from a quick test this ...
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1answer
482 views

MongoDB text index and text search

I have a mongodb collection db.articles,it has 2 keys ,"title" and "abstract".I want to do text search on these two keys.For example, the search text is "physics",and I want all the documents whose ...
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2answers
175 views

How do I create a global MongoDB Admin account to see all Dbs?

I'm working on MongoDB, sysadmin helped setup the install. I'm confused about MMS the Cloud Manager, I created an account for @admin database I authenticate successfully but do not see "test" ...
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129 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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24 views

Keep files in mongo as part of the data

I want to create a news app that works in the following way: The site will contain articles, and each article with have multiple versions. Each version is a docx file and the article itself does not ...
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1answer
21 views

Large `mongodump` followed by `mongorestore`

I have a fairly large (~240GB) Mongo database that I need to transfer across a sluggish network and onto a new server. Traditionally for these situations, I've found that a mongodump followed by a ...
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233 views

While installing Mongodb, getting “enabling http interface” message and stopped

I am getting following error while installing mongodb, $ mongod --directoryperdb --dbpath C:/mongodb/data/db --logpath c:/mongodb/log/ >mongodb.log --logappend --rest 2015-03-17T17:32:55.359+0530 ...
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155 views

Client not reading from Mongo secondary database

I've implemented a replica set that I'm using globally. I have my master in Oregon, US and 4 secondaries. California and Virginia, Frankfurt and Sydney. I also have web servers in those same regions ...