Redis: the AK-47 of databases

[ErrantX]

The title randomly reminded me of the AK-47 quote from Lord of War (an actually decent Cage film, and definitely a good bit of monologue):

Of all the weapons in the vast soviet arsenal, nothing was more profitable than Avtomat Kalashnikova model of 1947. More commonly known as the AK-47, or Kalashnikov. It's the world's most popular assault rifle. A weapon all fighters love. An elegantly simple 9 pound amalgamation of forged steel and plywood. It doesn't break, jam, or overheat. It'll shoot whether it's covered in mud or filled with sand. It's so easy, even a child can use it; and they do. The Soviets put the gun on a coin. Mozambique put it on their flag. Since the end of the Cold War, the Kalashnikov has become the Russian people's greatest export. After that comes vodka, caviar, and suicidal novelists. One thing is for sure, no one was lining up to buy their cars.

Only tangentially related :) but I thought worth sharing. Anyone care to write a redis version?

[nickpinkston]

I'll only be pedantic about them rarely being forged (mostly stamped) and definitely still having problems of overheating. Try firing one on full auto for more than one clip - better have gloves...

They are great weapons though. I've never cleaned mine or had a jam. I hope this database is that good!

[jtdowney]

It reminded me of the AK-47 quote from Jackie Brown:

AK-47. The very best there is. When you absolutely, positively got to kill every motherf@#$%r in the room, accept no substitutes.

[keiferski]

Supposedly the Ak 47s used in the film were real, as real Ak 47s are less expensive than fake ones. But I'm not sure where I heard this, or if it's even true.

[btipling]

This is somewhat related:

http://i.imgur.com/Tz0m3.png

[dennisgorelik]

The largest chunk of export from Russia is oil and gas, not weapons.

[Duff]

I doubt the actual weapon was profitable. They literally made like 75 million of the things. The Soviets may have made a few bucks setting up factories in the 3rd world for licensed production.

[apl]

  > In the spirit of full disclosure, I’m a newb to Redis. My
  > knowledge is basically the contents of this post (at the
  > time of writing). I don’t use it in production (yet).
  > Likewise I’m no expert in AK-47s (I’ve never even fired
  > one) or guns in general. I’m aware via notoriety alone.

Fantastic quote. So you're hardly familiar with either component of your simile, but you'll post it anyway? I really don't expect New Yorker-esque editing from bloggers, but that's simply not very substantial writing.

No wonder people make fun of the so-called "NoSQL movement."

[mrkurt]

Expert knowledge of an AK-47 wouldn't have improved the post and he managed to expose me to some bits of Redis that I wasn't previously aware of. That makes it more substantial than half the shit that ends up on Hacker News. :)

[zach]

Yes, bloggers talk about things they just learned about rather than something they're 360-degree experts about.

But that's good. It helps them -- it reinforces their learning and they certainly find out if they got something wrong -- and it helps us -- readers see a lot of articles pop up right when people are interested in and passionate about learning something, rather than months later when they know it all and have moved on.

Early blogging is quick iteration of knowledge. Blog about something you learned today, not years ago.

[dschobel]

It still has value according to the two-step HN algorithm of fact-finding.

step 1. Someone posts something (anything will do) on a blog

step 2. HN tears it apart and reconstitutes it with some decent approximation of truth and usually a fair bit of insight.

Basically, the source content is just the jumping off point. The blogs serve as a focal point for directing the HN hive's attention for a while.

You could post a story titled "Sarah Palin is more influential than the Pope but less influential than the iPhone" and fill it with lolcat pictures and still get an interesting discussion here.

Why? Because smart people are awesome.

[sfphotoarts]

I thought it was a well written article that was a good read. Possibly the author was demonstrating humility rather than ego.

[techiferous]

Consider the blog post a conversation starter. You don't have to be an expert in a topic before you can start a useful online discussion about it.

[mxavier]

Your last sentence is pretty flawed/ad-hominem. That being said, I do agree in the sense that the comment at the end of the post annoyed me and degraded the value of the article. Certainly, blog about whatever you want, but if you just picked up some new technology, don't write a link bait title and post it on HN. HN needs more breathless hype articles like I need a bullet in the head.

[zeteo]

"According to AK-47 legend, assault rifles were not popular because of their tendency to consume large amounts of ammo. The Soviets embraced the idea and simply supplied their troops with more ammo. Kinda like Redis and RAM."

That's obviously just a legend. This debate was actually carried out in the 2nd half of the 19th century, starting with the Civil War. (Many repeating rifle designs were offered to the Union. Quartermasters repeatedly shut them down on account of expected difficulties with ammo supply. After much time and effort, a few repeating rifles made it through, particularly to the cavalry, where they proved quite decisive in the last year of the war. See Five Forks, for instance.)

[iujyhgftrgh]

The British army only just relented - the new SA80 is the first fully automatic rifle to be standard issue.

[jacquesm]

Being the AK-47 of databases is not a bad way to be known.

That said I hope the author will revisit the topic when he has more knowledge of the subject matter, such as when using it in production for a while on a fair sized project with a lot of users. That's where the rubber meets the road, first impressions tend to gloss over the areas where the meat is.

[regularfry]

> That's where the rubber meets the road, first impressions tend to gloss over the areas where the meat is.

One hopes the meat is not between the rubber and the road. That would be unfortunate.

[IgorPartola]

Eek. Locking the entire data set to perform transactions? Isn't that so... MyISAM? Does rolling the transaction back work? The optimistic lock is not a great solution either: instead of deadlocking while waiting for a lock to be released, you are now stuck in a while (!saved) loop. Imagine two web pages trying to update the same resource at the same time.

Also this part of the config:

  save 900 1
  save 300 10
  save 60 10000

is not at all obvious. Maybe it's better documented in the sample config.

[code_duck]

According to the first comment, the part about locking the whole data set for MULTI is not accurate. Only the connection calling that is stalled, which makes perfect sense.

[MichaelStubbs]

The configuration options you have quoted are made extremely obvious in the sample configuration and are explained very well. See:

  # Save the DB on disk:
  #
  #   save <seconds> <changes>
  #
  #   Will save the DB if both the given number of seconds and the given
  #   number of write operations against the DB occurred.
  #
  #   In the example below the behaviour will be to save:
  #   after 900 sec (15 min) if at least 1 key changed
  #   after 300 sec (5 min) if at least 10 keys changed
  #   after 60 sec if at least 10000 keys changed

[pietern]

It's called optimistic for a reason. You assume there is low contention and configure your client to have random back off.

[jcromartie]

Maybe not, but I found the docs in about 10 seconds.

http://redis.io/topics/persistence

[xd]

MyISAM doesn't support transactions.

[draebek]

Factual incorrectness aside, and even speaking as a person that doesn't have much to do with anything other than SQL RDBMSes: this style of presentation piqued my interest in Redis. Seeing how fast and easy it was to get up and running, seeing how simple the protocol was, and getting a smattering of its features in this very terse format was effective on me.

[jamesli]

The author needs to know more about databases before claiming something is the AK-47 of the subject. It kinds of reminds me of those guys who think they are gurus just because they know some rarely used Linux commands, while in fact they don't have good understanding of OS. :)

[simonw]

What do you think he's missing? The comparison seems rather apt to me - Redis is shockingly simple and surprisingly effective compared to other persistence options.

[jwr]

The information about transactions in this article is wrong. Read the redis docs he actually points to for an accurate description.

This article should not get upvoted.

[fedd]

and the title?

[adamtj]

"The entire dataset is in RAM."

How can they guarantee that, when RAM is little more than a disk cache on modern operating systems? Is there a syscall that prevents specified pages of virtual memory from being paged out to disk? Or is Redis implemented as a kernel module?

[antirez]

Redis uses a memory layout that, unless the instance is completely idle, will make it very easy to touch every page even if there are just a few queries per second.

So fare in two years we never saw an instance where there was a latency problem because part of the dataset was swapped on disk by the OS. This is why we currently don't use mlockall().

[wingo]

Your swap should be off, and there is mlockall(2).

The kernel does let userspace have a /little/ fun on its own.

[Periodic]

In another comment, someone compared the PUB/SUB feature of Redis to ZeroMQ. Can the PUB/SUB feature of Redis function as a queue system for many common uses, or is there another significant difference that sets a full queue implementation apart? I ask because I am not particularly familiar with Redis, my queue usage has been fairly simple so far and I would enjoy simplifying my technology stack by combining the two if it makes sense.

[dorkitude]

Redis is great for small things. Massive scale players in the write-heavy owrld can rarely consider it in its current form.

[X-Istence]

"Pub/Sub is a unique and useful feature."

Pub/sub exists in a multitude of different pieces of software. ZeroMQ has a pub/sub feature. PostgreSQL has the NOTIFY/LISTEN command which is also a Pub/Sub channel allowing all those listening to be notified of certain events.

This is by no means unique to Redis. It is very useful, so I'll agree with that!

[malkia]

I served in the bulgarian army with this weapon, and it was very easy to handle. That's all I can say

But every weapon was a bit off, so you had to get used to it (I guess that might be the same for all weapons).

[mono]

The total number of the AK-type rifles made worldwide during the last 50 years is estimated at 90+ millions. Does the title implies that Redis will handle this amount of values too?

[mjgoins]

This one of very few google hits for the phrase "get the juxt".

[fedd]

AK of DBs should be used for some Russian DB! or Chinese...

okay okay. i hereby patent the definition 'an iPhone of databases' :)