_id In Mongodb

MongoDB company formerly known as 10gen, founded in 2007, in 2013 received a sum of 231 million U.S. dollars in financing, the company's market value has been increased to 1 billion U.S. dollar level, this height is well-known open source company Red Hat (founded in 1993) 20 's struggle results. High-performance, easy to expand has been the foothold of the MongoDB, while the specification of documents and interfaces to make it more popular with users, this point from the analysis of the results of Db-engines's score is not difficult to see-just 1 years, MongoDB finished the 7th ...

Http://www.aliyun.com/zixun/aggregation/13461.html ">mongodb and Cassandra are the two most popular NoSQL databases, MongoDB is the NoSQL field is worthy of the popularity of the king, while the Cassandra is the perennial occupation of the column storage field chief, compared with the hbase of concern for many reasons have been second. Recently Mydrive soulutions operation and Frame ...

http://www.aliyun.com/zixun/aggregation/13461.html"> MongoDB, formerly known as 10gen, was founded in 2007 and after receiving a total of $ 231 million in 2013, the company's market capitalization has risen to 10 Billion dollar level, which is the result of 20 years of Red Hat, a well-known open-source company founded in 1993. High performance and easy scalability have been the foundation of MongoDB and meanwhile standardized documents ...

1.count Count returns the number of documents in the collection &http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;db.refactor.count () No matter how large the collection is, the number of documents can be returned quickly. You can pass the query, MongoDB calculates the number of query results Db.refactor.count ({...).

NoSQL Recent momentum is good, http://www.aliyun.com/zixun/aggregation/13461.html ">mongodb is one of the Jiao jiao, oneself learn nosql when also reference a lot of information, The final decision to start from the MongoDB, the most important reason has two: 1 oneself is a simple amateur, all problems I think whether there is a simple way to solve, rather stop to think a lot of time, also do not want to use stupid method to do immediately, and Mong ...

To ease restrictions on the organization's large data services, Red Hat integrates 10gen MongoDB data into its new Identity Management Pack Rhel suite. 10gen Product Marketing Director Kellystirman that "a more robust identity management system it has a central infrastructure through which companies can be used for identity management in many different types of applications." "With the unification of MongoDB and Red Hat authentication management systems, stores that already use Rhel will be easier to build and run using Mon ...

One-to-one relationship: Embed, such as http://www.aliyun.com/zixun/aggregation/10619.html "> User information collection has Address field, Address field has three fields of province, city, county. Modeling is as follows: a one-to-many relationship: An article has multiple comments, for 1 to multiple relationships because MongoDB has a size limit of 16M (higher than v1.8 ...) for single documents (document).

&http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;1.find MongoDB uses Find to query. The query is to return a subset of the files in the set. The child collection ranges from 0 documents to the entire collection. The first parameter of find determines which documents to return. The form is also a document that describes the details to be queried. The empty query document {} matches the entire contents of the collection. If you don't specify ...

India's unique identification project (also known as the Aadhar Plan), which recently completed the collection of demographic and biometric data, is currently the largest of its kind in the world. The project, which has been in operation for several years, has been subject to conflicting voices from all sides, from privacy and security to other sources. At the same time, the latest developments in the Aadhar project have raised concerns about its methods of capturing, storing, and managing data, especially an American start-up company, Mongo ...

India's unique identification project (also known as the Aadhar Plan), which completed the collection of demographic and biometric data earlier this week, was more than 500 million Indians-the largest of its kind in the world today. The implementation of the project has been accompanied by conflicting voices from privacy and security as well as other aspects. The latest developments in the Aadhar project have raised concerns about its methods of capturing, storing, and managing data, especially an American start-up company ...