3 ms·
Is this really a brilliant idea though? Everybody knows RAM became cheaper cheaper, while mechanical disk can't be made faster, and SSD have reliability limits
by jokoon 8y ago
Is this really a brilliant idea though?
Everybody knows RAM became cheaper cheaper, while mechanical disk can't be made faster, and SSD have reliability limits.
It seems entirely logical to expect databases to work on RAM first and then commit on disk for a large performance improvement.
- antirez 8y agoWhen I started Redis people were like FTW data in memory?!
- jokoon 8y agoI was talking to a database teacher, and I tried arguing about ACID on an in memory database, arguing that there was a minimal window for database corruption in a transaction system, since the worst case scenario would seem to be a loss of very few transaction. He was not really listening to what I was saying or my arguments, because a system like redis seems like a more than acceptable compromise. It still seems a few people are reluctant to an in-memory database.
- benmmurphy 8y agoVoltDB is a probably a better example of an in-memory database with ACID semantics. Redis usually won't be deployed in a way where it fsyncs after each write operation because it runs too slow. You need to do some tricks like batching fsyncs to get decent performance and I don't think Redis has support for this. However, SSD fsync performance seems very high. I remember benchmarking an EC2 i3 instance that was giving 20000 fsync/s but if redis is giving you like 80k writes/s then even fsync this fast is going to be a bottleneck. [https://redis.io/topics/benchmarks https://redis.io/topics/benchmarks] I think people who are deploying redis are willing to tolerate lower durability guarantees for the extra performance. A lot of the time redis is some kind of cache and there is a way of reconstructing the real data from more durable storage in the case of failure. Or people are willing to lose a second of data or whatever fsync interval people are using.
- finnh 8y agos~FTW~WTF~ of course, _now_ they are like "FTW" :)
- mparr4 8y agoThis is the definition of hindsight bias. The best ideas often seem obvious in retrospect.
- jokoon 8y agoWhat I am saying is that this idea is totally obvious, but until somebody implements it to show it works, nobody dares to try it because it sounds like a bad idea.
- Retra 8y agoI've had plenty of good ideas that I haven't bothered to implement because I have no need for the solution. That doesn't mean if someone else implements the idea that I'll have hindsight bias about its value. It means it wasn't valuable enough to me to direct my behavior.