Create a new function from an existing function in Postgres?

Question

I have created a function function_1() in Postgres.
Now I want to create another similar function function_2() and copy the content of function_1().

Any Postgres command line can do that?

So far I only used copy&paste method in the command line to create function_2() (need to change the function name to "function_2" after paste)

Answer 1

If you are using the GUI pgAdmin, you can simply select the function in the object browser and open the reverse engineered SQL script in an SQL editor window.

There is a dedicated item in the options to automate it:

Options - Query tool - Query Editor - Copy SQL from main window to query tool

Answer 2

pg_dump the function definition, or use the pg_get_functiondef function to get the function definition. Modifying it is up to you.

If you're trying to programmatically create functions you might be better off with PL/PgSQL's EXECUTE command and the format function to create dynamic functions.

It's pretty unusual to need to do this, suggesting you're probably doing something that's much more easily done another way.