Questions tagged [mongodb]

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

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1answer
171 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 query ...
5
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1answer
706 views

MongoDB working set size on capped collection larger than capped collection size?

On my database server right now I have 16GB of ram and an 8GB capped collection with about 4GB of indexes. So I may understand this wrong but shouldn't this only ever use around 12GB of my RAM or ...
0
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1answer
190 views

The sort column must be the last column used in the index - MongoDB Indexing Advice

MongoDB docs advices that: The sort column must be the last column used in the index Here is the example: db.foo.ensureIndex({a: 1, b: 1, c: 1}) Good: find(a=1).sort(a) find(a=1).sort(b) find(a=...
4
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2answers
2k views

collection partitioning in mongodb

Is there any semantic like table partitioning in MongoDB? My data is not that much that it would need sharding. but data is not important(but not completely useless) after several months.
4
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2answers
2k views

Import and Export database in Mongo just like MySQL

I am newbie to the Mongo.Before this I have worked only with MySQL.In MySQL we can import and export database easily.I want to know is there any option available in Mongo to import and export database ...
7
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1answer
1k views

How to store and query products the price of which depends on a complex set of conditions?

I haven't decided on a database. I have expirience with MySQl and I'm intrigued by MongoDB. Let the products be packages of cable tv providers: { name: "Virgin TV", price: 20 }, { ...
11
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3answers
15k views

How should I store time series in mongodb

I need to create a database of time series, and perform the following tasks: create new time series update existing time series query one or several time series at once (for instance all time series ...
4
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2answers
1k views

Design the big data with mongo db

I'm working now on the implementation of the following feature: Say I have a collection in mongodb with millions of entries (very big say 100M), each entry is of type {"uniqId", "properties"} for ...
8
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2answers
4k views

How to index dynamic attributes in MongoDB

I have following kind of data (simplified a bit from my real case) in MongoDB: { "name":"some name", "attrs":[ {"n":"subject","v":"Some subject"}, {"n":"description","v":"Some ...
16
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1answer
4k views

How do databases store index key values (on-disk) for variable length fields?

Context This question pertains to the low-level implementation details of indexes in both SQL and NoSQL database systems. Actual structure of the index (B+ tree, hash, SSTable, etc.) is irrelevant as ...
7
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1answer
2k views

Mongo Map-Reduce or Sharding?

So I asked this question: Setting up Mongo with clustering But I didn't know enough until I read the answers and did more research. Is it better to use Map-reduce or sharding for fast-paced ...
6
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3answers
2k views

Setting up Mongo with clustering

I'm going to start using Mongo as a database but I will not have it clustered at first. Can I use Mongo on a single machine, then later come back, cluster it and capitalize on the sharding? Or can I ...
4
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1answer
1k views

Would appreciate some suggestions on how I should model this data

I am setting up a website that will have users. Users can search for songs and (if signed in) save them to a playlist or their library of songs. I want it to be like iTunes in that all the songs on ...
3
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2answers
568 views

How to check the pre-allocated database file of MongoDB is Used or not?

We have been using MongoDB for a few weeks. One thing we could not understood is Pre-allocated file. Is there any way to check whether the pre-allocated file is currently used by MongoDB or not? We ...
19
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5answers
5k views

Infrastructure for Highly Concurrent, High Write DB

My requirements are: 3000 Connections 70-85% Write vs Read Currently, we are maxing out a High-CPU, Extra Large Instance at 700 connections. All 8 cores are maxed. We think it's the number of ...
36
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4answers
30k views

Difference between MongoDB's find and findone calls

I am working on a project and I am unsure if there is a difference between the way the find cursor works and the way the findOne cursor works. Is findOne just a wrapper for find().limit(1)? I was ...
3
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2answers
193 views

What are the best Database Analytics Companies for analyzing several 1000s or Mio. of products,sum them together and analyze them for statistics?

We will get several thousands products in our database. The problem is that one product can have several different names e.g. "iPad 16GByte UMTS schwarz" or "iPad 16GB 3G black" and so on. But they ...
6
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1answer
2k views

In MongoDB, is having lots of small collections better than having one huge collection?

Huge collections have huge indexes that may not fit into RAM. Is that problem entirely solved with sharding ? If I have lots of small collections with small indexes, what are the options for storing ...
11
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2answers
878 views

Is sharding effective for small collections?

It looks like database sharding is great if I have huge collections. What if I have lots of fairly sized collections ? Let's say that for 1 collection of 100 000 000 documents (not very big comments) ...
8
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2answers
893 views

Is there any way to efficiently perform the equivalent of DENSE_RANK in MongoDB?

SQL Server and Oracle both have DENSE_RANK functions. Is there a way to do something similar in MongoDB without having to resort to MapReduce? In other words, suppose you have a T-SQL select clause ...
13
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4answers
734 views

Good Resources on Operating/Administering MongoDB

What are the best resources for learning how to operate and administer MongoDB? There are plenty of resources on developing against it - which actually creates a problem when you've got plenty of ...
18
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2answers
1k views

CouchDB vs MongoDB [closed]

Evaluating document-oriented storage, what are the pros and cons of CouchDB vs MongoDB?

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