How to Obtain the Full Source Code of a PostgreSQL Function

Learn how to easily retrieve the complete source code of a PostgreSQL function, including its definition right down to the input and output arguments.
---

Visit these links for original content and any more details, such as alternate solutions, comments, revision history etc. For example, the original title of the Question was: How to get the full source code of a postgresql function

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding PostgreSQL Function Definitions

When working with PostgreSQL, you may find yourself needing to retrieve the full definition of a function, not just its body. This is particularly important when you want to know the input arguments and output types clearly. The common SQL query used to fetch function details often falls short, leaving vital information like CREATE OR REPLACE FUNCTION statements out.

In this guide, we’ll guide you through the simplest way to get the full source code of a PostgreSQL function, ensuring you have all the information you need at your fingertips.

The Common Approach

Many developers start with the following SQL command to get the body of a function:

[[See Video to Reveal this Text or Code Snippet]]

Limitations

While this query returns the function’s source code, it does not include:

The complete definition (e.g., CREATE OR REPLACE FUNCTION my_func(args, ...))

Information about input arguments and output types

This means you might still need to dive into the code to understand how to use the function properly, which can be inconvenient and time-consuming.

The Solution: Retrieving Full Function Definitions

To get the complete source of a PostgreSQL function, including its definition and argument types, you can use the built-in PostgreSQL function pg_get_functiondef(). This function is designed for precisely this purpose.

The SQL Query

Here is the SQL command you should use:

[[See Video to Reveal this Text or Code Snippet]]

How It Works

pg_get_functiondef(oid): This function retrieves the complete definition of the specified function, which includes:

The function’s full declaration (including any input parameters and return types)

The body of the function

pg_proc: This system catalog contains all the information about functions defined in the database.

proname: Replace 'functionname' with the actual name of the function you are interested in.

Example Use Case

Suppose you have a PostgreSQL function called calculate_area, and you want to obtain its full definition. You would execute:

[[See Video to Reveal this Text or Code Snippet]]

This will return a complete definition like:

[[See Video to Reveal this Text or Code Snippet]]

From this output, you can easily see both the input parameter (radius) and the return type (float8), along with the entire function body.

Conclusion

Now you know how to effectively retrieve the full source code of a PostgreSQL function using the pg_get_functiondef() method. Armed with this knowledge, you can avoid unnecessary digging through code and enhance your workflow efficiency. By taking just a few seconds to run this command, you'll quickly have all the relevant information you need!

Feel free to implement this method in your future database interactions and share it with your fellow developers who might find it helpful.