Wix Code on noSQL Db?

Last night, it suddenly dawned on me that I prob. lived under the false assumption that Wix Code was a simplified interface over a relational database. I thought the absence of foreign keys, indices, transaction management and locking was done to make things simpler. I had heard of another type of database, referred to as noSQL, but I have never worked with them.
I did a little reading and … they don´t support that ACID-stuff and speak about Collections instead of Tables, just like in WIx Code.
So is it true? Is Wix Code built upon a noSQL DB? If so, I apologize for having made pointless feature request about locking and transactions. I have prob. not read thru doc. well enough.