How to write a custom window function for presto?

@scotty_walker 

To write a custom window function for Presto, you will need to follow these steps:

1. Define the function signature: Determine the input parameters and return type of your custom window function.
2. Implement the logic of the custom window function: Write the SQL logic or Java code that defines the behavior of the custom window function. This can include calculations, aggregations, or any other operations you want to perform on the window of data.
3. Compile and package your custom window function: If you are writing the function in Java, you will need to compile the code and package it as a JAR file. Make sure to include any dependencies that are required for your function to run.
4. Register the custom window function in Presto: Use the CREATE FUNCTION statement in Presto to register your custom window function. This statement should include the function name, input parameters, return type, and the location of the JAR file containing the function code.
5. Test the custom window function: Write test queries in Presto that use your custom window function to verify that it is working as expected.

By following these steps, you can create and use a custom window function in Presto to perform advanced data processing tasks on windows of data within your queries.