PREFINALS | Introduction to NoSQL Database Management Systems | Advanced Database Systems

Big Data

It is used to label large volumes of data that push the limits of conventional software. This data is usually unstructured or semistructured and may originate from a wide variety of sources: social media postings, emails, electronic archives with multimedia content, etc.

Big data

It generally refers to a set of data that displays the characteristics of high-volume, high-velocity, and high-variety (the 3 Vs) information assets that demand cost-effective, innovative forms of information processing for enhanced insight and decision making.

Volume

the quantity of data to be stored, is a key characteristic of big data. The storage capacities associated with big data are extremely large.

Velocity

another key characteristic of big data. This refers to the rate at which new data enters the system as well as the rate at which the data must be processed.

Variety

In a big data context, it refers to the vast array of formats and structures in which the data may be captured.

Volume, Velocity, Variety

The 3 Vs:

NoSQL database management systems (NoSQL DBMS)

A new generation of database management systems that is not based on the traditional relational database model (SQL) which met the two criteria: 1. The data is not stored in tables. (Like SQL) 2. The database language is not SQL.

NoSQL

It is also sometimes interpreted as 'Not only SQL' to express that other technologies (besides relational DBMS) are often used for storing Big Data and in massively distributed web applications. technologies are especially necessary if the web service requires high availability (i.e., data in social media like Facebook).

NoSQL

It excels in its ease of use, scalability, resilience, and availability characteristics. Instead of joining tables of normalized data, ______ stores unstructured or semi-structured data, often in key-value pairs or JSON documents.

Key-value (KV) database

It is the simplest of the NoSQL data models. It stores data as a collection of key-value pairs. The key acts as an identifier for the value. The value can be anything such as text, an XML document, or an image.

Key-value (KV) database

The database does not attempt to understand the contents of the value. The database simply stores whatever value is provided for the key. It is the job of the applications that use the data to understand the meaning of the data in the value component. There are no foreign keys. Relationships cannot be tracked among keys at all. Greatly simplifies the work that the DBMS must perform, making KV databases extremely fast and scalable for basic processing.

Column-oriented databases

It can refer to traditional, relational database technologies that use column-centric storage instead of row-centric storage. More efficient for optimizing read operations to store the data in relational tables, not per row, but per column.

Column-oriented databases

All columns in one row are rarely needed at once, but there are groups of columns that are often read together. To optimize access, it is useful to structure the data in such groups of columns—column families—as storage units.

Document-Oriented databases

____________-____________ __________ are conceptually similar to keyvalue databases, and they can almost be considered a subtype of KV databases. A document database is a NoSQL database that stores data in tagged documents in key-value pairs. Unlike a KV database, where the value component can contain any type of data, a document database always stores a document in the value component. The document can be in any encoded format, such as XML, JSON (JavaScript Object Notation), or BSON (Binary JSON).

Document-Oriented databases

Tags are named portions of a document. Although all documents have tags, not all documents are required to have the same tags, so each document can have its own structure. Tags in a document database are extremely important because they are the basis for most of the additional capabilities that document databases have over KV databases

MongoDB

It is a cross-platform, open-source, document-oriented database that provides high performance, high availability, automatic, and easy scalability. It is highly optimized for JSON. It stores data in flexible JSON documents, which means the columns may vary from document to document, and the data structure may be reformed over time.

Database, tables, column, rows

SQL vs MongoDB: SQL has;

Database, collections, fields, documents

SQL vs MongoDB: MongoDB has;

Database

MongoDB groups collections into databases. A single instance of MongoDB can host several databases, each of which can be thought of as completely independent.

Collections

It can be thought of as a table with a dynamic schema.

Document

is the basic unit of data for MongoDB, roughly equivalent to a row in a relational database management system (but much more expressive).

_id

Every document has a special key, "_", that is unique across the document's collection.

create a new database

In MongoDB, If there is no existing database, the given command below will automatically _ __ ____ ______.

db

To check the currently selected database, use the ___ command:

show dbs

To query the database list, use the command: