Calcite recognizes Database from RelNode

Question

RelNode print each specific dialect query

Hi all,

I started to use Apache Calcite a few days ago to understand how it works. I created a JSON model with 3 different schema/databases

1. Postgres
2. CSV
3. Mongo

Calcite works fine and is connected to all databases, for each one I implemented algebra and build a RelNode that I'm able to run and retrieve the result for each one.

My question is, from each RelNode I would like to print each specific query used from calcite for each technology to retrieve the data, how I can do it?

Thank you for your help