You want to know the queries postgres uses when you execute a command
This can be done with a startup parameter
You can start psql with the -E parameter. Started with -E psql will write the SQL commands that genereate the output for your queries. Postgresql provides an sql compliant INFORMATION SCHEMA interface which can be queried for more information about your database.
About the Author
Wim Peeters is electronics engineer with an additional master in IT and over 30 years of experience, including time spent in support, development, consulting, training and database administration. Wim has worked with SQL Server since version 6.5. He has developed in C/C++, Java and C# on Windows and Linux. He writes knowledge base articles to solve IT problems and publishes them on the Lubby Knowledge Platform.