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If you’ve been in a job interview, you’ve probably asked what NoSQL is. Are you familiar enough with it? What is MongoDB? This article will explain NoSQL databases and get acquaintable with them. Maybe soon, we will break the horn of this giant programming job interview! If you are not familiar with databases or databases, you can read our article entitled ” What is a Database” before reading this tutorial? Read.

In traditional programming, databases are usually of the SQL type, a relational database. Databases are simple relationships and are usually hassle-free to work with. But these types of databases have a big problem. This problem manifested itself when the world’s software giants such as Google, Amazon, and Facebook needed to analyze large amounts of data or Big Data.

Due to their structure, relational databases were inefficient and inefficient for analyzing big data. Of course, it was almost impossible to use the tabular structure used in relational databases in some cases. Because of this, storing large volumes of non-structured data drastically reduced the speed and efficiency of these databases. Until the NoSQL databases came into being. So as you can guess, the main purpose of creating NoSQL databases is to work with unstructured and bulky data.

We said that the problem with SQL-based databases is their structure. But what is this structure like, and why does it cause such problems? To understand the answer to this question, we need to know a little about the structure of SQL databases.

Familiarity with the structure of the SQL database

If you have experience using SQL, you know that you must always obey the rules. You must place a set of identifying information with the same specifications in your respective tables. In fact, in SQL, you have to have specific answers to each of these questions:

• What entities do you have? In what categories is the information to be storeable? Like user categories, news, comments, and هستند are all examples of existence. Usually, each entity is considered in the form of a table.
• What are the properties of each of your tables? What specific information do you intend to store in it? Remember that these properties must be constant! Because each of these properties means a column of your table. For example, the user table can contain columns of name, surname, age, e-mail, etc. This number of columns should not be different for each user.

• What information does each of your data contain? Each new data is stored in the form of a new row in the table you want. For example, a row is formed for each new user with the columns of name, surname, age, and, in the user table.

• How does each of your tables relate to other tables or tables? For example, each user can be a member of one or more classrooms, and each classroom can contain a set of users.

All of these properties of your database are stored in SQL with a Schema structure. Schema is a fixed structure and acts as the skeleton of a building. Everything is mounted on it and completed based on it. By now, you may have figured out the main problem with this type of database storing unstructured data! In storing such data, the properties of each data are not always fixed, which makes SQL inoperable and sometimes unusable for them.

NoSQL Databases

Database [ltr] ( Sot Only SQL ) NoSQL [/ ltr] Unlike the SQL type, they use non-dynamic Schema structures. This eliminates the need for developers to formulate strict structures before creating databases. These databases can be of many types, and unlike SQL, they use XML or JSON to store the data. Here are some common types of NoSQL databases:

• Key-Value Databases:  In this type of database, information is stored in key-value or Key-Value pairs. The keys play the role of the identifier of each data. We can use them to store or find different amounts of data. Key-value databases are the most widely used NoSQL databases due to their ease of operation.

• Wide-Column Database: You might think that column database are the same as relational databases. But this is just the appearance of such databases, which is similar to a relational type. We have said that in databases, it is necessary that the number and type of properties of each entity and the values ​​within it be known and fixed. However, each column in different records can contain data of different structures and types in column databases.
• Document Database: We use JSON or XML documents to store the data in such databases. Document databases are commonly used to store and use scattered and unstructured data.
• Graph Databases: In this type of database, we use graphs to store entities and their relationships. Graphical databases are suitable for cases where we need to make multiple connections between tables.
• Multimodel Databases: Multimodel databases are a combination of other types of databases. In this type of database, we can store data in different ways and use them.

Advantages of using NoSQL

NoSQL databases have many advantages that make them the best choice for large, distributed systems. In general, these advantages can be summarized as follows:

• High Scalability: NoSQL databases can be easily expanded with Horizontal Scaling. This feature reduces the complexity and cost of scaling the software.
• High Performance: In NoSQL distributed systems, by automatically duplicating NoSQL data on multiple servers worldwide, the delay in sending a response from the server is minimized.
• Availability: In NoSQL distributed systems, the database is still accessible and responsive due to the automatic copying of data on different servers when one or more servers become inaccessible.

Conclusion

We have found that relational and SQL-based databases, while having the advantage of being structured and regular, are not suitable for unstructured systems or big data analytics. This means that their advantage becomes the biggest disadvantage in many large systems such as search engines. To solve this problem, NoSQL databases such as MongoDB were introduced. NoSQL databases are easily used in distributed systems and improve their performance. Have you ever used relational databases? What do you think about using this type of database?