What exactly is NoSQL?

Question

What exactly is NoSQL? Is it database systems that only work with {key:value} pairs?

As far as I know MemCache is one of such database systems, am I rig

Answer 1

What is NoSQL ?

NoSQL is the acronym for Not Only SQL. The basic qualities of NoSQL databases are schemaless, distributed and horizontally scalable on commodity hardware. The NoSQL databases offers variety of functions to solve various problems with variety of data types, where “blob” used to be the only data type in RDBMS to store unstructured data.

1 Dynamic Schema NoSQL databases allows schema to be flexible. New columns can be added anytime. Rows may or may not have values for those columns and no strict enforcement of data types for columns. This flexibility is handy for developers, especially when they expect frequent changes during the course of product life cycle.

2 Variety of Data NoSQL databases support any type of data. It supports structured, semi-structured and unstructured data to be stored. Its supports logs, images files, videos, graphs, jpegs, JSON, XML to be stored and operated as it is without any pre-processing. So it reduces the need for ETL (Extract – Transform – Load).

3 High Availability Cluster NoSQL databases support distributed storage using commodity hardware. It also supports high availability by horizontal scalability. This features enables NoSQL databases get the benefit of elastic nature of the Cloud infrastructure services.

4 Open Source NoSQL databases are open source software. The usage of software is free and most of them are free to use in commercial products. The open sources codebase can be modified to solve the business needs. There are minor variations in the open source software licenses, users must be aware of license agreements.

5 NoSQL – Not Only SQL NoSQL databases not only depend SQL to retrieve data. They provide rich API interfaces to perform DML and CRUD operations. These are APIs are move developer friendly and supported in variety of programming languages.

Answer 2

I used something called the Raima Data Manager more than a dozen years ago, that qualifies as NoSQL. It calls itself a "Set Oriented Database" Its not based on tables, and there is no query "language", just an C API for asking for subsets.

It's fast and easier to work with in C/C++ and SQL, there's no building up strings to pass to a query interpreter and the data comes back as an enumerable object rather than as an array. variable sized records are normal and don't waste space. I never saw the source code, but there were some hints at the interface that internally, the code used pointers a lot.

I'm not sure that the product I used is even sold anymore, but the company is still around.