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How to speed up MongoDB Map Reduce by 20x. Group by dates in mongodb. MapReduce - MongoDB. Map/reduce in MongoDB is useful for batch processing of data and aggregation operations.

MapReduce - MongoDB

It is similar in spirit to using something like Hadoop with all input coming from a collection and output going to a collection. Often, in a situation where you would have used GROUP BY in SQL, map/reduce is the right tool in MongoDB. Overview map/reduce is invoked via a database command. Typically the database creates a collection to hold output of the operation. map and reduce functions are written in JavaScript and execute on the server. Command syntax: * finalize - function to apply to all the results when finished keeptemp - if true, the generated collection is not treated as temporary.

Output options MongoDB v1.7.3 and below: If you do not specify a value for out, then the results will be placed into a temporary collection whose name will be given in command's output (see below). MongoDB 1.7.4+: the output options have changed. For example: Additional options within out objects are: Result object. Nosql - MongoDB nested array query. Aggregate functions - Can the MongoDB aggregation framework $group return an array of values. MongoDB Aggregation Framework Examples in C# - Mikael Koskinen. MongoDB version 2.2 was released in late August and the biggest change it brought was the addition of the Aggregation Framework.

MongoDB Aggregation Framework Examples in C# - Mikael Koskinen

Previously the aggregations required the usage of map/reduce, which in MongoDB doesn’t perform that well, mainly because of the single-threaded Javascript-based execution. The aggregation framework steps away from the Javascript and is implemented in C++, with an aim to accelerate performance of analytics and reporting up to 80 percent compared to using MapReduce. The aim of this post is to show examples of running the MongoDB Aggregation Framework with the official MongoDB C# drivers. Aggregation Framework and Linq Even though the current version of the MongoDB C# drivers (1.6) supports Linq, the support doesn’t extend to the aggregation framework.

Aggregation Framework and GUIDs If you use GUIDs in your documents, the aggregation framework doesn’t work. The example data These examples use the following documents: Example 1: Aggregation Framework Basic usage. MongoDB with C#: Deep Dive. MongoDB with C# Beginners' guide to using MongoDB 2.2 and the official C# driver. Download demo - 707.3 KB Introduction This article attempts to highlight the latest developments in both the Mongo open-source document database and the open-source official C# driver and to supplement the previous reviews on CodeProject in the light of these improvements.

Beginners' guide to using MongoDB 2.2 and the official C# driver

Overview of Document Databases. Document databases store information relating to a record in a contiguous blob of data known as a document . A document’s structure usually follows the JSON format and consists of a series of key-value pairs. Hosted Web Server for MongoDb. There is free web hosting of MongoDb at MongoHQ . Desktop Installation of MongoDb and the C# Driver All you need to get started is on the Mongodb website. The Database Structure Every record does not need to contain every field. MongoDB and C# Download sample project - 111 KB Introduction Most likely you have used a relational database and been fairly happy with it.

MongoDB and C#

I know I have. Be it SQL Server or MySQL, I know how to use my tools efficiently to push, pull, and transform the data I need. When we sit down to analyze a project, we'll debate over the language, the servers, etc..., but we never talk about what type of database fits the problem. So what am I getting at? As it turns out, there is another type of database. In this article, I'd like to help you get started with MongoDB, from install to your first project. Getting MongoDB The MongoDB site has a downloads link sitting right at the top. After you have downloaded it, you can simply unzip it anywhere on your box.

At this point, you are running the MongoDB server on localhost, port 27017. There is a shell you can run to play around with the database if you'd like. MongoDB Introduction We are going to create a simple little test project that simulates a blogging system.