PostgreSQL is among the two most popular open source databases, first one being MySQL. MySQL is a relational database management system (RDBMS), whereas Postgre is an object- RDBMS.
For this, let us first know what is RDBMS?
1. INTRODUCTION TO RDBMS:
What Is DBMS?
Data is nothing but information in qualitative and quantitative manner. Hence, data should be stored and maintained, accurately and quickly. In simple language, DBMS (Database Management System) is a system that is used to store and manage data. Hence, while selecting a DBMS following points must be kept in mind:
1) Support for large amount of data
2) Data sharing, concurrency and locking
3) Data Security
4) Data Integrity
5) Fault tolerance and recover.
2) Data sharing, concurrency and locking
3) Data Security
4) Data Integrity
5) Fault tolerance and recover.
1. Support for large amount of data:
Each and every DBMS has a capacity to store large amount of data.
Each and every DBMS has a capacity to store large amount of data.
2. Data sharing, concurrency and locking
Data can be shared by two or more users. The same data accessed by multiple users simultaneously, this is known as data concurrency. Whereas locking means, if same data is accessed and manipulated by multiple users, then certain problems may arise. Hence, DBMS locks data that is being manipulated by one user to prevent another user from modifying the same data at the same time.
Data can be shared by two or more users. The same data accessed by multiple users simultaneously, this is known as data concurrency. Whereas locking means, if same data is accessed and manipulated by multiple users, then certain problems may arise. Hence, DBMS locks data that is being manipulated by one user to prevent another user from modifying the same data at the same time.
3. Data Security
Access to data only for authorized users.
Access to data only for authorized users.
4 .Data Integrity
Data should remain accurate and consistent, without having similar entries or garbage values.
Data should remain accurate and consistent, without having similar entries or garbage values.
5. Fault tolerance and recover
DBMS should be able to run in spite of errors and have capacity to rectify the errors in real-time. And in the event of failure, allow backup provided, its available.
DBMS should be able to run in spite of errors and have capacity to rectify the errors in real-time. And in the event of failure, allow backup provided, its available.
What is RDBMS?
RDBMS is a data model in which data is stored in form of a table (includes rows and columns).
RDBMS is a data model in which data is stored in form of a table (includes rows and columns).
In the above image, Louis Figo is the entity, whereas Phone-454333 is its attribute.
What is SQL?
SQL stands for Structured Query Language and is used to manipulate and retrieve data from a RDBMS. It comprises of 4 commands, namely:
SQL stands for Structured Query Language and is used to manipulate and retrieve data from a RDBMS. It comprises of 4 commands, namely:
a) DDL (Data Definition Language): used to define the data. For example, CREATE TABLE
b) DML (Data Manipulation Language): commands such as, INSERT and DELETE used to manipulate data.
c) DCL (Data Control Language): commands are used to control the access to data. For example, GRANT
d) Query (Retrieving data): is used to retrieve data using SELECT command.
b) DML (Data Manipulation Language): commands such as, INSERT and DELETE used to manipulate data.
c) DCL (Data Control Language): commands are used to control the access to data. For example, GRANT
d) Query (Retrieving data): is used to retrieve data using SELECT command.
After understanding DBMS and RDBMS, let us know what ORDBMS ie Postgre is all about.
In ORDBMS data is represented in the form of objects. ORDBMS is nothing but a combination of Object Oriented-DBMS and RDBMS. Object Oriented-DBMS allows the user to extend the system by incorporating new/ custom/ abstract data type—a user can integrate geometric types and operations, as well as spatial indexing. In order to incorporate special concepts into a RDBMS, it is essential to re-organize the database structure entirely. This violates the data independence principle, therefore it is not a feasible option with RDBMS.
ليست هناك تعليقات:
إرسال تعليق