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Comment by mike_hearn | Hacker News Reader

Isn't that just logging transactions? The talk says Datomic is fundamentally different, but I don't see anything on his list of features at the end that's not been available for years in commercial databases.

https://oracle-base.com/articles/11g/flashback-and-logminer-...

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Datomic is built around a simple log of fully serial transactions. It doesn't have MVCC or other such magic to coordinate concurrent writers, and this means (1) read-only queries don't require open transactions and (2) the whole stack can have mechanically sympathy with this accrete-only design, affording massive efficiency and scaling potential. Capabilities may look similar on the surface but that's where the similarity ends. Take a look at slides 13 & 14: https://qconsf.com/sf2012/dl/qcon-sanfran-2012/slides/RichHi...

Datomic is much more similar to Delta Lake or Apache Iceberg than to a classic RDBMS like Oracle in that respect - but then that analogy severely undervalues it's information modelling qualities.

if the log is as efficient and scalable why is MVCC even a thing? TBH the description on wikipedia looks identical to Datomic to me, minus the persistent data structures. Does it just come down to rectangular fixed width structs of RDBMS give better query performance?

https://en.m.wikipedia.org/wiki/Multiversion_concurrency_con...

Yes, Oracle has had proper/comparable time travel for years.

Datomic is interesting with the Datalog interface combined with first-class temporality. One can likely achieve everything similarly in Oracle (but your pocketbook won't like it.)

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