Introduction to MongoDB (original) (raw)

You can create a MongoDB database in the following environments:

• MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud
• MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
• MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

To learn more about creating a MongoDB database with the Atlas UI, see Get Started with Atlas.

A record in MongoDB is a document, which is a data structure composed of field and value pairs. MongoDB documents are similar to JSON objects. The values of fields may include other documents, arrays, and arrays of documents.

The advantages of using documents are:

• Documents correspond to native data types in many programming languages.
• Embedded documents and arrays reduce need for expensive joins.
• Dynamic schema supports fluent polymorphism.

MongoDB stores documents in collections. Collections are analogous to tables in relational databases.

In addition to collections, MongoDB supports:

• Read-only Views
• On-Demand Materialized Views

MongoDB provides high performance data persistence. In particular,

• Support for embedded data models reduces I/O activity on database system.
• Indexes support faster queries and can include keys from embedded documents and arrays.

The MongoDB Query API supports read and write operations (CRUD) as well as:

• Data Aggregation
• Text Search and Geospatial Queries.

Tip

• SQL to MongoDB Mapping Chart
• SQL to Aggregation Mapping Chart

MongoDB's replication facility, called replica set, provides:

• automatic failover
• data redundancy.

A replica set is a group of MongoDB servers that maintain the same data set, providing redundancy and increasing data availability.

MongoDB provides horizontal scalability as part of its _core_functionality:

• Sharding distributes data across a cluster of machines.
• Starting in 3.4, MongoDB supports creating zones of data based on the shard key. In a balanced cluster, MongoDB directs reads and writes covered by a zone only to those shards inside the zone. See the Zonesmanual page for more information.

MongoDB supports multiple storage engines:

• WiredTiger Storage Engine (including support forEncryption at Rest)
• In-Memory Storage Engine for Self-Managed Deployments.

In addition, MongoDB provides pluggable storage engine API that allows third parties to develop storage engines for MongoDB.