What does it mean for a data lake to be transactional?

Transactional data lakes is a common way to refer to the abilities enabled by these new table formats, but what does that mean?

Let’s start by looking at the definition of a database transaction in general, from Wikipedia (https://en.wikipedia.org/wiki/Database_transaction):

”A database transaction symbolizes a unit of work, performed within a database management system (or similar system) against a database, that is treated in a coherent and reliable way independent of other transactions.”

What this means is that you have the ability to update a database in a way that may potentially make multiple updates as part of the transaction, and you have the guarantee that all the individual updates will work and be applied consistently, or the whole transaction will fail. That means that if there are five updates as part of the transaction, and the third update fails, then the two previous...