What’s the difference between SQL and NoSQL?
SQL databases are primarily referred to as Relational Databases (RDBMS).
NoSQL databases are primarily referred to as Non-relational or Distributed Database.
SQL
- SQL databases are table based databases.
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Have predefined schema.
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Are vertically scalable.
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Use SQL (Structured Query Language) for defining and manipulating the data.
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A good fit for the complex query intensive environment
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Emphasize ACID properties (Atomicity, Consistency, Isolation and Durability)
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Examples include: MySql, Oracle, Sqlite, Postgres and MS-SQL.
NoSQL
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NoSQL databases are document based, key-value pairs, graph databases.
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Have dynamic schema.
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Are horizontally scalable.
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Focused on the collection of documents.
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Not ideal for complex queries.
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Follow the Brewers CAP theorem (Consistency, Availability and Partition tolerance )
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Examples include: MongoDB, BigTable, Redis, RavenDb, Cassandra, Hbase, Neo4j and CouchDb.
Diving deeper
- Relational database: is a collective set of multiple data sets organized by tables, records and columns.
- Document database: pairs each key with a complex data structure known as a document. Documents can contain many different key-value pairs and nested documents.
- Key-value database: are the simplest NoSQL databases. Every single item in the database is stored as an attribute name (or ‘key’), together with its value.
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