Jampp Presto User Defined Functions

This repository contains the JSON_SUM aggregation function. It combines all the JSONs in a column by adding the shared keys and appending the rest. It's used as an example for our How to write custom Presto functions blogpost.

Build

Inside the presto-udfs folder, run:

mvn clean package

Docker testing

To setup a Docker container with the UDFs, run:

docker run --name presto -p 8080:8080 -v $PWD/presto-udfs/target/presto-jampp-udfs-0.306/:/usr/lib/presto/plugin/udfs prestosql/presto:346

This will add the UDFs to the /usr/lib/presto/plugin/ folder inside the container.

You can then connect to the Presto server through the Presto CLI. If you run the SHOW FUNCTIONS; command, you should see the json_sum on the list (it will appear once per input type).