pymongo mapreduce example

Common aggregation operations in MongoDB include aggregation, mapreduce, and group. First, add some test data: db. things. insert ({x: 1, tags: [dog, cat]}) db. things. insert ({x: 2, tags: [cat]}) db. things. insert ({x: 2, tags: [mouse, cat, dog]})

1. install and use MongoDB A) download MongoDB. Note that 32bit can only store 2 GB of content (32-bit builds are limited to around 2 GB of data ). B) Configure MongoDB. config and run the command line mongod.exe -- config/path/to/Your/MongoDB.

Original English: Http://www.mongodb.org/display/DOCS/MapReduce MapReduce is used primarily as batch data and aggregation operations in MongoDB, more like Hadoop, where all inputs come from a combination, all output to a set, more like a group

Transferred from: http://www.cnblogs.com/cswuyg/p/4355948.html1. Count Statistics result errorThis is because the distributed cluster is migrating data, which results in a count result value error and requires the use of aggregate pipeline to obtain

The recent year is busy with data processing related work, with MongoDB very much, the following is the practice process of q&a, follow-up will not be updated regularly.1. Count Statistics result errorThis is because the distributed cluster is

Tag: Date writing C # IDF DFS aggregation replace network Apr MongoDB is a document-oriented database that is simple and easy to operate. You can set the index of any property in the MongoDB record (for example: Firstname= "Sameer",

The recent year is busy with data processing related work, with MongoDB very much, the following is the practice process of q&a, follow-up will not be updated regularly. 1. Count Statistics result errorThis is because the distributed cluster is

"Database Commands""How the Command Works"The commands in MongoDB are actually implemented as a special type of query that is executed against the $cmd collection. RunCommand simply accepts the command document and executes the equivalent query, so>

MongoDB is one of the most popular NoSQL databases today. During the summer vacation, I finally had time to read some articles about it from the MongoDB authoritative guide and NoSQL Fan, below I will briefly summarize some interesting things of

MongoDB Report Instance Scenario selectionBackground introductionIn our production environment we are using replica sets, in order to allocate the business pressure of the database server, we split the database to run on a different replica set.We