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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Taking more time for execution

I am trying the below loop with inserts under Mongo 2.6 (windows) environment and it took nearly 30+ minutes for completion and also created an index as well during execution automatically.. I am bit ...
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MongoDB on RAID0?

As I'm reading production notes of mongodb I found that RAID0 is not recommended: Most MongoDB deployments should use disks backed by RAID-10. Avoid RAID-0 with MongoDB deployments. While RAID-0 ...
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Mongo repairDatabase procedure

I need to run a repairDatabase in mongo in order to reclaim some os disk space. Can anyone provide feedback on the following procedure: let me know if its correct, if I'm missing anything, if the ...
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15 views

MongoDB failover reasons

I have a replica set on MongoDB with 3 members - primary, secondary and arbiter. One day I came and saw that primary and secondary have switched. I'd like to find a reason for the failover that caused ...
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17 views

Mongo range query became extremely slow on large collection

I have a collection which has 50 million records in it. After using wired Tiger its size became only 3 GB (2 GB data 700 MB index). I have created index on this collection. But when i do a range query ...
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Mongo 3 Intermitted Craches

Currently running two VMs with fresh installs of Ubuntu 14.04 x64 and Mongo 3 Stable. Our processing VM is doing great under heavy loads, however our production VM seems to have Mongo crashing once ...
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7 views

Multiple databases through a single connection MongoDB, GridFS

I want to use GridFS in your project. As the main database using mongodb. My application can do only one connection to the database (such conditions). Can I make calls to other databases using the ...
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1answer
41 views

Mongo Db server status with wired Tiger

I was testing my DB with Mongo 3.0 wiredTiger setup. After restoring my database with wiredTIger i ran db.serverStatus. I found following in console output. "bytes currently in the cache" : ...
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2answers
25 views

Does MongoDB support two 2-way synchronization

We are looking at moving our data from IBM Domino to another backend. One of the things Domino does really well is replicate (or synchronize as they call it) between a Server and Clients. That means ...
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29 views

Mongo DB accessesNotInMemory issue with RAM size

I am using Mongo Replica set and it seems to be working fine but when i check db.serverStatus i saw that there are lots of accessesNotInMemory for all The DBs in my mongo instance. I checked MY RAM ...
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17 views

Mongo 3.0 release for Cent OS

Can any one tell me When Mongo team will release 3.0 production release. Also will it be available for cent OS as we are shifting g our production boxes from RHEL 6 to cent OS and on Mongo Download ...
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16 views

How to create and select entities in MongoDB?

I'm a newbie in MongoDB and I'm trying to understand how to create objects there and how to select them in comparison with relational databases. So I need an example how to perform these things. ...
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13 views

Error while doing in replicaset in windows (mongodb)

I tried doing the replicatset in windows, but im getting the below error. I checked the mongo process and killed the existing process. Even though the error exists. help me on this pls Thx ...
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How the statement based replication works internal on secondary node of mongodb?

Mongodb supports statement-based-replication. Would like to know, how the statement based replication converts the code internally on secondary node of mongodb. Is that working related to the ...
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28 views

Sorting on compound Indexes

This may be a novice question but could it be possible query here. If I have a compound Index as { a: 1, b: 1, c: 1, d: 1 } Is this query possible? db.data.find( { a: {$gte:1,$lt:2}, b: { $gt: 3} ...
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18 views

Mongodb schema design validation

I am building an app which allows users to do some "tasks" to earn points. The "tasks" are part of a "campaign" which themselves are a part of "brands". I am confused about the schema for storing the ...
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9 views

MongoDB sharding one collection on single server (2 drives)

I have one single server with two drives (SSD 256GB, HDD 1 TB). What I want to do is to store the newest documents in collection on SSD. Older documents can be stored in HDD drive. Is it possible in ...
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16 views

Can we resize a already capped collection in mongo db [duplicate]

I have a capped collection whose initial size i gave 3 GB. Can I modify its size again i mean reducing or increasing both way as per need? is there any command to do it. ...
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80 views

MongoDB: co-locate the mongos process on application servers

I would like to ask a question about a best practice described in this document: http://info.mongodb.com/rs/mongodb/images/MongoDB-Performance-Best-Practices.pdf Use multiple query routers. Use ...
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18 views

Good way to store daily train data in MongoDB

I am preparing to collect large amounts of information about trains in my country. Each train in my country has a number. I've already collected all of these numbers. There are about 4000 of them. ...
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21 views

MongoDB auto-failover: election doesn't happen

I have the following working replica set: { "_id" : "repl1", "version" : 6, "members" : [ { "_id" : 0, "host" : "hostA", ...
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10 views

Error running --eval mongodb command

I tried to run javascript (js) file to get shard's config server information, it runs fine in mongo shell but as result is too large to analyse on command prompt, i tried to save the output in a file ...
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23 views

MongoDB stops responding after 2 days of working

I've written small application in Python (I used Twisted). Program receives data and writes it to MongoDB. Every 2 days MongoDB stops responding: 2015-02-11T10:47:20.918+0100 [initandlisten] can't ...
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1answer
27 views

Extremely long startup time for MongoDB server

I have a MongoDB Server with just over 2 million documents in one collection. Individual documents can contain large amounts of data (some are several megabytes each) but none of that data is in ...
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12 views

The MondoDB.org “Category Hierarchy” Example

I am creating an MVP app for a client but I am skilled in iOS mainly with only some DB experience. I'm using MongoDB. The schema is for a Product Catalog for small markets. The client wants a ...
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10 views

Mongo find query is not using indexes in java code but working on mongo cosole

I found a strange issue. When i run mongo query from my java code with explain true it does not show me index used in the query but when i run it using mongo console it works fine . ...
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What “fromRouter” option means on MongoDB aggregations?

Recently i notice that a parameter fromRouter" : true exists on mongoDB aggregations. I search the MongoDB documentation and google for it, but i didn't found anything about it. Can anyone explain ...
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40 views

Why does mongodb require three config servers

The official mongodb documentation states to use three config servers. They say its for redudancy, because 1 server would be a point of failure.... but why not 2? in a production sharded cluster, if I ...
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20 views

Saving String as unique number in Mongo

I have a field in my collection which is a String in nature. When i run aggregation for this field in data it takes considerable time in aggregation. Total 6 million records are in collection which ...
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13 views

MongoDB Sparse Index Query

I have around 40 million records in my collections but some million documents doesn't contain a field "catId". Sample Document : { "_id": ObjectId("5458b1a24669c5c0d66ae658"), "host": ...
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13 views

what model should i use for store detections time series in mongodb?

i have cloud site with many hosts and virtual machines inside of it. I receive from some software many different metrics values regarding vms usage (cpu load,free ram,energy consumption and so on). ...
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1answer
28 views

MongoDB Hashed Shard Keys Selection

I have a DB which holds very simple documents called "Item": {_id:<ObjectId>, playerId:int, isRead:bool, content:string} containing about 80M documents. Each Item belongs to a certain player, ...
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24 views

Data containing list of all the domain names. MongoDB or MySQL?

Data containing list of all the domain names (currently present in the Internet world), along with few attributes (5-6 or maybe 10, each attribute being a column) will be considered as Big Data? ...
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21 views

MongoDB Disk Usage with Capped Collections

I am using MongoDB using C#. I am currently using only a single server. Since I have to create Table events for MongoDB collections I have created a single replica set(primary). And using ...
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18 views

Installing Mongodb on windows

Does anyone have any adverse experience of running mongodb on windows? What is the recommended platform to run mongodb?
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11 views

what is default balancing window in MongoDB

I have read about balancing window in MongoDB document. I see mongo tell about how to modify balancing window but I don't see the default of balancing window. I see only one document about chunk size ...
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12 views

Using MongoDB with circular object references

Please forgive me from the beginning. I am brand new to document oriented databases and I am sure that I will need guidance to reform the question in order to get answers. I am looking to use MongoDB ...
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13 views

why my data is not being sharded?

I am using mongo 2.6.7 I deploy a sharding cluster follow the guide: http://docs.mongodb.org/manual/tutorial/deploy-shard-cluster/ My sharding cluster include: - two replica sets (one primary + one ...
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1answer
24 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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17 views

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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15 views

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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1answer
22 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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1answer
53 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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26 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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1answer
40 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
40 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
68 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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1answer
17 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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31 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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2answers
95 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 ...