Incremental models: Excluding specific columns from being updated (creation date eg)

[snorten]

Hi everybody,

This is my first post, so... nice to meet you and SQLMesh is killer!
But I cant find a good solution to this one: Preventing a specific column (created_date) from getting updated during the merge process in an "incremental by unique key" model.

Possible solutions so far, to my knowledge:
a) Use "when_matched" to specify updates on all columns except this special one and be very careful when doing model changes, to not forget something in the future. I feel this approach being just too much overhead, especially on wide tables.
b) Self joining the resulting model and doing something like coalesce({{this_model}}.created_date, current_timestamp), which could mean to join in very large tables to get one piece of information and slowing down things. Also, it would require "hard-defining" column types in order for self joins to work.

"Maybe solutions" that dont seem to work so far:
c) Column defaults (Not supported for my iceberg tables on trino)

"Future solutions" (?)
d) An additional "merge_exclude_columns" parameter (dbt has this)
e) Extending the "when_matched" part, in order to just override the specified column-updates, without the need to re-code the whole statement for the rest

What else could I try?

Greetings