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pjtatlow / jammdb

Just Another Memory Mapped Database
Apache License 2.0
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Power outage tolerance #14

Closed D1plo1d closed 1 year ago

D1plo1d commented 1 year ago

How tolerant is JammDB to random power outages when it is writing data? Is data corruption a risk with JammDB if the machine is unexpectedly stopped mid-write?

pjtatlow commented 1 year ago

It should handle power outages just fine. Underneath it is a memory mapped file that is synchronously fsync'd when a write is committed. If the write isn't committed properly it should fall back to its state in the previously written transaction.

D1plo1d commented 1 year ago

Awesome, that's exactly what I want! This is a bit off topic but @pjtatlow, while I've got you here, I noticed there haven't been as many commits in the last year and was wondering about maintenance status, are the fewer commits just a sign that the library is generally just stabilized and working well? Is this ready for production?

pjtatlow commented 1 year ago

@D1plo1d I don't know if anyone out there is using this in production yet, and I know of at least one issue where there is some sort of race condition that ends up corrupting the database file 🤦🏽‍♂️

I haven't been able to reliably replicate it and the original use case I meant to use this for didn't work out, so I haven't had the time or ability to fix that yet!

D1plo1d commented 1 year ago

@D1plo1d I don't know if anyone out there is using this in production yet, and I know of at least one issue where there is some sort of race condition that ends up corrupting the database file 🤦🏽‍♂️

Oh no! Yeah, database corruption is top of my mind. Well, while I imagine I'll stick with sled DB for now but I'll keep an ear out for JammDB updates - I quite appreciate the design of JammDB which at least at my high level understanding sounds much simpler then Sled.

I haven't been able to reliably replicate it and the original use case I meant to use this for didn't work out, so I haven't had the time or ability to fix that yet!

Those are the worst kind of bugs. Best of luck!

pjtatlow commented 1 year ago

@D1plo1d Feel free to check out 0.8.0, I added a strict mode which ensures the database isn't corrupted before finalizing commits, and I also fixed those issues it's been having. Let me know if you're able to try it out!