Example of a UDF written in python on Redshift

redshift_python_df_example.sql

create function f_extract_query_param(query_string VARCHAR, param VARCHAR) 
returns varchar 
STABLE
AS $$

    # Split on ampersand and then on =, ensuring every param has a pair
    params = query_string.split("&")
    # split(.., 1) because there might be multiple '=' in the param 
    kp = [p.split("=", 1) for p in params]
    # create dict, with "" for missing values where the key is not an empty string
    # ''.split('=', 1) -> ['']
    keys = {k[0]: k[1] if len(k) > 1 else "" for k in kp if k[0]}
    return keys.get(param)

$$ LANGUAGE plpythonu