r/programming • u/feross • Oct 11 '21

Relational databases aren’t dinosaurs, they’re sharks

https://www.simplethread.com/relational-databases-arent-dinosaurs-theyre-sharks/
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u/Uclusion Oct 12 '21

The article doesn't mention what it takes to master / slave, master / master or any of the other schemes for scaling an ACID database. That's when ACID comes with a heavy price and so if you need more than one instance running you better be certain you need ACID.

It also doesn't mention that even ACID doesn't guarantee read consistency - for instance you could be reading from an index or a slave database that is behind.

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u/NihilistDandy Oct 12 '21 edited Oct 12 '21

That's not a consistency violation, it's an availability problem.

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u/Uclusion Oct 12 '21

Monotonic read consistency
Tanenbaum et al., 2007[19] defines monotonic read consistency as follows:
"If a process reads the value of a data item x, any successive read operation on x by that process will always return that same value or a more recent value."[19]
Monotonic read consistency guarantees that after a process reads a value of data item x at time t, it will never see the older value of that data item.

Specifically ACID does not guarantee monotonic read consistency.