What Java engineer to master? What an introduction to MongoDB? Domestic line companies such as Alibaba, Tencent, Baidu and so the use of MongoDB, in the recruitment process HR job seekers will be emphasis on the mastery of the MongoDB. For a Java engineer, he wanted the famous enterprises, high salaries necessary to master technology companies valued, give us today to share knowledge MongoDB entry point.
MongoDB is a file storage based on distributed, open source, high performance, free mode, the database using the C ++ language for the document. It supports flexible and dynamic document model, high availability Replica Set, horizontal expansion Sharding, secondary indexes, dynamic queries, a series of powerful full-text search, syndication framework, MapReduce, GridFS, geographical index, memory engine, the geographical distribution.
Want quick start MongoDB, you need to know the following points:
Database (database): a warehouse, which can be stored in the collection.
Collection (collection): The concept is equivalent to MySQL tables, similar to an array, you can store documents in the collection.
Document (document): Document is the smallest unit in the database, storage and content we are operating documentation.
MongoDB basic instructions:
show dbs / databases: View all the current database
use (database name): Go to the specified database
db: displays the database is currently located
show collections: the collection displays all the current database
MongoDB specification:
Some key characters and document retention and conventions
1) is case-sensitive;
2) type of region value (e.g., numeric characters and channeling);
3) the same document can not have the same key;
4) to distinguish the sequence of key documents;
5) key button can not \ 0 whitespace end;
6)% _ reserved characters.
Set of naming conventions:
1) a set of name can not be the empty string;
2) a set of names can not \ 0 null characters as the end;
3) a set of system names can not begin with, the system reserved characters;
4) collection name can not be there most $ naming system reserved.
Database naming convention: (UTF-8 strings)
1) all lowercase;
2) up to 64 bytes;
3) can not empty string;
4) can not contain spaces $ \ / (\ 0 whitespace).;
5) Reserved string has (admin, local, config).
MongoDB principle:
1) transmission format is BSON;
2) transport protocol is mongo seal coat and TCP / ip Agreement;
3) the namespace file (local.ns) and data files (local.0, local.1);
4) using memory-mapped storage engine.
MongoDB has a rich data model, with the increasing amount of data and scalable clustering, database is the best big data era. If you want to quickly grasp MongoDB, the future of high-paying Java engineers can choose professional learning with you quickly get incredible Java technology.