The commit action ensures that the DATA CONSISTENCY of the transaction is maintained and it ends the current transaction in the section. Commit adds a new record in the log that describes the COMMIT to the memory. Whereas, a checkpoint is used for writing all changes that were committed to disk up to SCN which would be kept in datafile headers and control files.

SQL is a language for the database. It has a vast scope and robust capability of creating and manipulating a variety of database objects using commands like CREATE, ALTER, DROP, ETC, and also in loading the database objects using commands like INSERT. It also provides options for Data Manipulation using commands like DELETE, TRUNCATE and also does effective retrieval of data using cursor commands like FETCH, SELECT, etc. There are many such commands which provide a large amount of control to the PROGRAMMER to interact with the database in an efficient way without wasting many resources. The popularity of SQL has grown so much that almost every programmer relies on this to implement their application's storage functionalities thereby making it an exciting language to learn. Learning this provides the developer a benefit of understanding the data structures used for storing the organization's data and giving an additional level of control and in-depth understanding of the application.

PostgreSQL being an open-source database system having extremely robust and sophisticated ACID, Indexing, and Transaction supports has found widespread popularity among the developer community. 

References and Resources:

PostgreSQL Download

PostgreSQL Tutorial

SQL Guide

SQL Server Interview Questions

MySQL Interview Questions

DBMS Interview Questions

PL SQL Interview Questions

MongoDB Interview Questions

SQL Vs MySQL

PostgreSQL vs MySQL

Difference Between SQL and PLSQL

SQL Vs NoSQL

SQL IDE

SQL Projects