Main functional characteristics of MongoDB

MongoDB No-mode benefits
1, storage form, compared to the traditional relational database, it can use a table to store the original need to use a multiple table association to store the database. 2, storage dynamic, compared to the traditional database when you want to add a property value to the table big move, MongoDB document-oriented form can make its attribute value light meaning increase and delete. And the original relational database to achieve this need to have a lot of property sheet to support.
MongoDB Storage Features
3, MongoDB has two kinds of data writing mode, one is efficient fire-and-forget mode is to submit data to the database server not to the database server response. This is the database default mode. The other is a safe mode, is written in the same time with the server synchronization, when the security requirements of the data is suitable for safe mode. 4, MongoDB log function. Log function is to help restore the data integrity when the system down machine, by default MongoDB is turned on log function. Each database operation logs the log, so when the down machine restarts the server, the database server is able to recover the operations that were not completed before the log file. Of course, opening the log will inevitably affect performance, so users need to choose a suitable working mode according to their actual application. If you plan to use the No log mode, it is best to use the Copy cluster mode, which can reduce the risk of data loss. Index of MongoDB
5. MongoDB supports all indexing modes (ascending, descending, unique, composite, geo-spatial index) of relational databases, and also supports level two indexes (implemented by B-tree). Each collection supports 64 indexes
6, support the ad hoc queries users can define their own queries.
Cluster of MongoDB
7, MongoDB cluster mode is a master-slave mode cluster, where the primary server only one, support read and write, and from the server can have multiple only read operations. The main purpose of the cluster is to realize the failover mode through the redundancy of the data, thereby improving the usability of the database server. When one of the primary servers is automatically upgraded from the server to the primary server, the other drive client can automatically switch to the new master server as long as it is failover, working properly. And when the original primary server resumes work, it will automatically switch from the server.


Scalability of the MongoDB
8, MongoDB adopted the latest Low-cost horizontal expansion mode, relative to the traditional single node vertical expansion, can save success, but also has better reliability, better data processing performance.