MySQL的鍵值儲存以及與MongoDB的對比

Faster and faster, that is what we want from our databases. And the biggest roadblock for the MySQL Dragster is the speed of the hard disk, right? No, I'm not going to debate that, that is just the case. And how do you fix that then? Well, if what is limiting your dragster is a roadblock, then either you drive round the roadblock of you make it disappear faster, or in computer terms:

1. Avoid using the disk by instead putting as much data as you can in RAM
2. Use faster disks (like SSDs)

Now, to be honest, this analogy isn't that good because the performance limiting factor of the disk is so huge, and contrary to popular belief, it's not getting any better! But we have SSDs you say? Yes, that makes the hard drive faster, but the CPU and RAM are getting even faster! But let's assume that we have enough memory so we do not need the disk? Will just about everything go at the speed of light? Nope, what happens here is that stuff that wasn't even noticeable in terms of limiting performance when the disk was there, as disk-I/O is such a huge bottleneck, suddenly shows it's dirty face!

Like this:  As the CPU cores are getting faster, but not that much faster anymore, due to physical limitations, we have more and more of these CPU cores instead. And suddenly, any limitation in getting those CPUs to work well together suddenly turns into a major headache! Like a mutex shared by all threads. Like the Query Cache mutex in MySQL for example!

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