Supports scaling and geospatial indexing capabilities
No concepts of tables, rows, columns
No features of ACID compliance, JOINS, foreign keys etc
MongoDB stores data as Binary JSON Documents (also known as BSON)
MongoDB is built for scalability, performance and high-availability
MongoDB provides High Availability, Scalability and Partitioning at the cost of Consistency and Transactional support
MongoDB is a platform of choice for applications needing a flexible schema, speed and partitioning capabilities while it may not be suited for applications which require consistency and atomicity
MongoDB uses a JSON (JavaScript Object Notation) based document store to store the data
Documents have dynamic schema - means documents in a same collection can have different fields or structure or maybe common fields can have different type of data
It is implemented using C++ language
Mongo provide support for secondary indexes, for users to query using query documents
It provides support for atomic updates (atomicity) at per document level
It provides replica set which are master-slave replication with automated failover and built-in horizontal scaling via automated range-based partitioning
Polymorphic/flexible/dynamic schema - implies that documents within the same collection can have same or different set of fields or structure, and even common fields can store different type of values across documents
JSON stands for JavaScript Object Notation
JSON is both easy for humans to read and edit & easy for computers to store data, parse and output
JSON basic data types such as Strings, Floating point numbers, Boolean values, Null value, Arrays, Hashes
JSON documents begin and end with curly braces
JSON is composed of Fields, and each field has a key and a value & are commas separated
JSON documents are analogous to objects, structs, maps, or dictionaries, in other languages
All keys are surrounded in double quotes
Keys and values must be separated by colons
Arrays (defined by square brackets []) and objects can themselves be values and nested in any combination
Arrays contain an ordered, comma separated list of values & are analogous to arrays lists, vectors, or sequences
BSON is an extended form of JSON data model - supports embedding or arrays and objects within other arrays
BSON allows navigation to the objects to build indexes and match objects against query expression both on top-level and nested BSON keys, The Identifier (_id)
Key is used for querying data from the documents
A key uniquely identify each document within a collection. This is referred as _id in MongoDB
This key value is immutable and can be of any data type except arrays
In MongoDB, a database serves as a namespace for collections. Each database and collection combination define a namespace e.g. mydb.mycollection
Collections store individual records called documents
This hierarchy allows us to group together records of similar items within collections, and group collections required for the same application within the same database
MongoDB has a concept of capping the collection - helps in maintaining its replication logs
This means it stores the documents in the collection in inserted order and as the collection reaches its limit the documents will be removed from the collection in FIFO (First in First Out) order
Capped collection guarantees preservation of the data in insertion order, hence
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 4B7C549A058F8B6Becho "deb [ arch=amd64 ] https://repo.mongodb.org/apt/ubuntu bionic/mongodb-org/4.2 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb.listsudo apt update | sudo apt install mongodb-orgsudo systemctl enable mongod | sudo systemctl start mongodmongod --version checks the core database server or daemonmongo checks the database shellIn MongoDB Authentication and Authorization is supported on per-database level
Users exist in the context of a single logical database and are stored in the system.users collection within the database
System.users - This collection stores information for authentication and authorization on that database. It stores the user's credentials for authentication and users privileges information for authorization
The available roles are in mongoDB; -read, -readWrite, -dbAdmin, -userAdmin, -clusterAdmin, -readAnyDatabase, -readWriteAnyDatabase, -userAdminAnyDatabase, -dbAdminAnyDatabase
Create the admin
>use admin
>db.createUser({user: "AdminUser", pwd: "password", roles:["userAdminAnyDatabase"]})
>db.createUser({user:"josh",pwd:"root",roles:["root"]})
...
>db.auth("AdminUser", "password")
More commands >> reference
Syntax >use DATABASE_NAME
>use mydb
Insert at least one document to keep this database >db.users.insert({ id: 1})
Show databases >show dbs
Find current selected database >db
Delete database >db.dropDatabase()
Copy database >db.copyDatabase(fromdb, todb, fromhost, username, password, mechanism)
Create collection >db.createCollection(name, options)
Get collections information >db.getCollectionInfos(); e.g. >db.getCollectionInfos({ name: "accounts" });
Insert document >db.COLLECTION_NAME.insert(document)
Query >db.COLLECTION_NAME.find(condition)
More commands >> reference
Always disable the HTTP Status page & the REST configuration in the production environment
Use Firewalls - used to control access within a network;
Encrypt Data - file system level encryption and permissions should be implemented in order to prevent unauthorized access to the files
Encrypt communication - it is recommended to use SSL for communication between the server and the client
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*References*
- Database Systems: Design, Implementation, and Project Management, Springer.
Albert K W Yeung & G. Brent Hall- Database Systems: Design, Implementation, and Management, 12th ed.
Carlos Coronel & Steven Morris- Database Modeling and Design; Logical Design, 5th ed.
Taby Teorey et.al- Fundamentals of database systems, 6th ed.
Ramez Elmasri & Shamkant B. Navathe
Courtesy of …