> I didn't think an MVCC implementation could provide that level of isolation

MVCC needs a bit of additional logic ontop to be serializable - "Serializable snapshot isolation" is a good keyword to search for - But it's definitely possible.

https://courses.cs.washington.edu/courses/cse444/08au/544M/R...

https://drkp.net/papers/ssi-vldb12.pdf

https://wiki.postgresql.org/wiki/Serializable

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