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This sort of ignores the fact that most modern databases use MVCC style row versioning - they only "forget" that the leaf was once attached to the tree when it doesn't actually matter any more, and actually use exactly immutable type state in the interim.

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It is important for our celebrity driven tech culture for each generation to "invent" (or 'rediscover' more generously) extant (and far more rigorous) work by the workers of prior generations.

In which modern MVCC databases can you ask the results of a query if it had been made 1000 transactions before I started this transaction? MVCC is great for dealing with the problems caused by mutability with Concurrency. Datomic takes versioning and immutability a good bit farther than that.

I guess I read more into the last paragraph than I should have; it portrays the simple problem of read write concurrency as if nobody solved it yet. It was a really bad way for the author to end the post because it confuses what was written before.

Mind you, creating audit / history tables to allow querying of past state is an extremely common and very standard database pattern too. Though I will admit I have encountered systems where more than half the tables were being audit logged so it's interesting to think about a database where that was effectively the default.

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