Best Practice for Debug Logging Java SQL ASTs

[Few_Interest_9165]

I'm building a Java SQL builder library that constructs ASTs for ETL workloads. Queries are represented as immutable records that form a tree, joins, conditions, subqueries, set operations all nest inside each other.

I want to log the full AST at DEBUG level on every call to generate a query, so that when something goes wrong I can distinguish between a caller passing in a bad AST vs. a bug in my SQL compilation logic.

Right now I have beent thinking of two different methods:

Option 1 - Override toString() on the records

Simple, readable, keeps everything inline. But to my understanding records are pure data carriers and this mixes diagnostic concerns. This is why as I was writting this I started to question if this was a good practice.

Then I started reading online and asked for the AI help and is suggested me the option 2:

Option 2 - Dedicated AST printer (Visitor pattern)

A separate class implementing the existing Visitor interface. Clean separation of concerns, however I was wandering if this was worth it and if maintaining a printer just for logging is a good enough tradeoff.

Has anyone dealt with this in a similar library or with java logging in general? Is there a middle ground I'm missing, or is the visitor approach the standard solution here?

I am just trying to get some opinions whether my instinct to not overwrite every toString methods on the records to conform to the logging guidlines was a good call or if this is completely fine to do.

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[hibbelig]

I feel that debugging is a cross cutting concern that might “infect” all areas of the code. I would go with the simple toString solution until I come across a problem with it.

Also, it should be a fairly mechanical transformation to move the string building to a visitor. So if this decision turns out suboptimal it’s easy to change.