Postgres data stored in Parquet on S3: LTAP architecture explained

Maybe I'm too stupid to understand the article... How does this achieve performant querying for olap and oltp purposes?

Based on my understanding, olap queries will go to the parquet files which are stored in a columnar fashion and oltp style queries will go to a caching layer that sits on top of those parquet files?

What's the special sauce here? Seems like they're just caching the data which, for all intents and purposes, seems like the same solution of storing another copy of the data which is what they say they're avoiding.

So then would LTAP sit to both the left and the right of the medallion architecture? Meaning would you on the left of Bronze use it as an OLTP and to the right of Gold use it as an OLAP? Currently we've been mainly utilizing it to the right of Gold to develop analytic PERN applications that allow us to reuse the RBAC/ACLs set in Unity Catalog, but from this article it seems like that's only half of its utility?

Super cool stuff. Being able to combine your analytical platform and transactional database into one storage layer without having to set up ETL pipelines in between is really a game changer. Especially since it's just postgres, instead of some proprietary database.

Here's what I don't understand:

Part of the value of doing an ETL pipeline via streaming replication is you get the full history of data in a table. An SCD type 2 table where each row also has a valid_from and valid_to timestamp column.

How would someone do the same thing with this architecture?

I don't wanna see that S3 bandwidth bill after running some big query

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