create a snapshot on sources that already have some history

Jumping into the discussion to add one suggestion/idea. Sorry if this was already discussed, I couldn't find it.

One complaint I hear from time to time is that you can't create a snapshot if the source has duplicates.

Imagine we have a source like

id	status	date
1	created	2024-01-01
1	processed	2024-02-01

It would be nice if the snapshot, in its first run, could read this source and be built like

id	status	date	dbt_valid_from	dbt_valid_to
1	created	2024-01-01	2024-01-01	2024-02-01
1	processed	2024-02-01	2024-02-01	null

We could have something similar to incremental models

If the snapshot does not exist in the platform (first run), create a history of the source's data, instead of trying to insert only
if the snapshot exists in the platform, then go the default way

It would only work for the timestamp strategy, because the snapshot must know what is older and what is newer.

Just an idea, maybe there are other ways to do it. But just because it is bad when we can't create a snapshot on sources that already have some history.

By the way, loved that snapshots are in the spotlight! 🧡

Originally posted by @bruno-szdl in https://github.com/dbt-labs/dbt-core/discussions/7018#discussioncomment-9706404

dbt-labs / dbt-core

create a snapshot on sources that already have some history #10320