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PostgreSQL Database vs schema

PostgreSQL-Database-vs-schema

Difference between PostgreSQL Database vs schema

PostgreSQL database is a container containing all the schemas, records, logs, and constraints of the table. Databases are rigidly separated, which means that a user cannot access two databases together. In order to manipulate the data in the database of PostgreSQL, DML (Data Manipulation Language) commands are used.

PostgreSQL Schema defines the outline of how the data is logically structured and stored in the database. It contains all the tables, data types, indexes, functions, stored procedures, everything related to it. One can define the different Schema in a database for different people accessing the application in order to avoid conflicts and unnecessary interference. A diagram can be drawn in order to show the database schema of a table (showing the columns it contains, data types, key constraints, etc.) known as a schema diagram.

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Head to Head Comparison Between PostgreSQL Database vs schema (Infographics)

Below are the top 9 differences between PostgreSQL Database vs schema:

PostgreSQL-Database-vs-schema-info

Comparison Table of PostgreSQL database vs schema

Below given is the comparison table showing the head to head comparison between the PostgreSQL database and schema:

S.No. PostgreSQL database PostgreSQL schema

1.

 A database in PostgreSQL contains the subset of schema. It contains all the schemas, records, and constraints for tables. A Schema in PostgreSQL is basically a namespace that contains all the named database objects like tables, indexes, data types, functions, stored procedures, etc.
2. One database can contain any number of schemas that contain tables. Schema, on the other hand, contains the objects like data types, functions, operators, views, indexes, etc.
3. Databases in PostgreSQL are rigidly separated, which means one cannot use two different databases together. In order to use any other database, one needs to connect to it and use it. Unlike databases, schemas are not rigidly separated, which means one can use and access the objects of two or more schemas of the same database altogether.
4. The database is the main container having all the log files, data, and other schemas. Schema, on the other hand, is like the folder in the database used to group logical objects together.
5. A database is basically a collection of interrelated data and contains information about the considered object. Schema is the logical representation of the entire database.
6. Databases in PostgreSQL can be updated frequently. Once declared, Schema in PostgreSQL should not be changed frequently as it disturbs the whole organization of data of how the relationships are created between different tables, related stored procedures, etc.
7. In order to modify the data in PostgreSQL, DML statements are used. DDL statements are used to modify the data in PostgreSQL Schema.
8. Syntax to create a database in PostgreSQL is:

 

CREATE DATABASE db_name;

 

where,

db_name is the name of the database created by the programmer.

 Syntax to create a schema in PostgreSQL is:

 

CREATE SCHEMA schema_name;

 

where,

schema_name is the name of the schema to be created.
9. Syntax to drop a database in PostgreSQL is:

DROP DATABASE [IF EXISTS] db_name;

where,

db_name is the name of the database dropped by the superuser or database owner.

 Syntax to drop a schema in PostgreSQL is:

 

DROP SCHEMA [IF EXISTS] schema_name [, . . .] [CASCADE|RESTRICT];

 

where,

schema_name is the name of the schema to be deleted.

CASCADE: It will automatically drop all the objects of the schema like functions, tables, etc.

RESTRICT: It will refuse to drop the schema if it contains any objects like tables, functions, etc. By default, RESTRICT is set.

Key Differences of PostgreSQL Database vs schema

Some of the key differences between the PostgreSQL database and schema describing in detail are given below:

1. Schema in a database is basically the logical representation of a database that describes the whole database. It contains views, indexes, tables, data types, operators, etc. The schema defines the attributes of the database. In contrast, a database is the container that contains all the schemas, logs, records all the related data, constraints for tables, and is an organized collection of interrelated data.

2. DML (Data Modification Language) statements like INSERT, SELECT, UPDATE, DELETE are used in order to modify the data of the database, whereas, in order to modify the data in PostgreSQL Schema, DDL (Data Definition Language) statements are used like CREATE, DROP, ALTER, TRUNCATE, RENAME.

3. If we talk about the modifications, data of the database must be updated regularly with time, but modifications in the Schema must not be done frequently as it affects everything, be it values present in the tables, the relationship between tables (primary key, foreign key), related stored procedures, etc.

4. Schema in PostgreSQL uses the logical structure in order to store the data, but on the other hand, the database uses the physical memory in order to store the data.

5. As we have already said, the database contains all the schemas and the logs, and Schema contains all the tables, fields, indexes, etc. So the programmer can not create two tables with the same name in one schema. Though, it can be done in two different schemas. But it is possible that the user creates 2 tables with the same name in the two different databases. As both the databases are independent and not related to each other.

6. One cannot use two different databases together. In order to switch the database, the programmer needs to disconnect the previous one and connect the new one in order to use its tables and other related data, whereas it is possible to access 2 different schemas together if he/ she has the privilege to do so.

7. Schemas are generally used to organise the data of the database logically in a structured manner that would be easy to access and manage. Moreover, it allows multiple users to access the single database without interfering with each other. So Schemas play an important role when there are multiple users using the application and accessing the database in their own way or there are multiple applications using the same database. Database, on the other hand, contains all the Schemas created for different users.

Conclusion

The above description clearly explains what the PostgreSQL database and schema are and the major difference between the two. For a programmer working on the database, it is important to understand these basic concepts like database, schema, various data types, fields, etc., deeply in order to have a clear understanding while working on real databases.

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