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The point of this article is that Redis cannot be the "one true datastore". By "one true datastore", he means that Redis is the only data store you need in the
by weixiyen 16y ago
The point of this article is that Redis cannot be the "one true datastore". By "one true datastore", he means that Redis is the only data store you need in the stack, because it has an append mode that persists data in memory to disk.
The author's mistake is that he is setting up a strawman argument. I've yet to hear Redis claiming to be a end all be all solution for data storage. In fact, it would make sense that most production environments use Redis as the non-persistent cache layer backed by an ACID compliant datastore for the time being.
The author's second point is that Redis fails "at scale in production environments". I'm curious to see some examples here of production Redis failing and I'd like to know how those companies were using Redis. Either way, the scalability debate should wait until 2.2 is released, because 2.2 is supposed to address primarily multi-server Redis instances.
I think the main problem is just believing that there can be "one true datastore". Different technologies excel at different things. You pick what you want your app to do, and then take a look at the tools given to you and pick the best one for the job.
Redis happens to be a great choice for many things, but ACID compliant storage is not really one of them at the moment, although I suppose you could set up 2 Redis instances, one for fast in-memory usage and one that syncs to disk on every command for now.
From my experience, Redis is great for the following:
- Session storage
- basic LRU cache
- Publish / subscribe
- key value store where you want to manipulate data in the form of common data structures
- simple / medium complex queries
Redis is not good for:
- ACID compliant data storage AND fast in-memory access at the same time (the holy grail)
- Complex sql-like queries
Right now, if you try to make Redis persistent in the event of a crash (fsync constantly), you will get a performance hit because the writes to disk will be too frequent.
Antirez is trying to solve the problem of persistence while still keeping fast in-memory access. The author does not feel like Antirez will succeed here, and became "angry", which I find is a bit unreasonable.
I personally use Redis in production for what it's currently good for. If the persistence with speed issue is solved, all the better. It's not an all or nothing type of situation. The worst thing the author could do in this situation is to pick SQLite as your one and only data store for the entire stack. There's nothing wrong with having multiple types of datastores. In fact it is the norm and trying to fight against it at this time is kind of pointless.
- arnorhs 16y agoI absolutely agree. Also, complex queries should be handled by performing them periodically on your backend stroage offline, storing the results in something like redis and then simply read from the redis DB online. I think simple redis queries have the perfect level of data logic you would need just to be able to retrieve the corect/relevant results from the complicated queries you produce. There are so many people who have written about methods on how to do something like this, eg. facebook, disqus, etc.
- lvh 16y agoOut of interest, if I'm implementing an LRU cache, why would I use Redis instead of memcached?
- xd 16y agoIf it is a simple KV store then there is no reason to use Redis. If you want the ability to search keys then Redis will most likely suit you better.
- Mikushi 16y agoAgreed on that. Plus, i noticed a mistake made by a lot of people, Redis is NOT memcached. That's just as easy as that. You can use Redis the same way as you would use memcached, but that would be a waste. The power of Redis resides in its data structures and the usage you make of it. You can make some pretty powerful stuff, easily and with performance. Nested Comment system (https://gist.github.com/803251 https://gist.github.com/803251), autocomplete (http://pastebin.com/E5h1TLWz http://pastebin.com/E5h1TLWz), all of that with high performance over large dataset, and much more, stuff that is not doable with Memcached. Also, the role of Redis is not to replace SQL databases, i personally view it, and use it, as a complement to it, and it works just perfectly. (I am fully aware that the examples given are possible with SQL solution, but experience in production/development as shown me that Redis is easier and faster when it comes to not too complex operations like these ones)
- StavrosK 16y agoWhy wouldn't you? As I understand it, Redis is a superset of memcached (since you can turn disk writes off) and comparable in speed. I, at least, use it as a memcached replacement for storing sessions with the added benefit of not having them all expire if I need to restart the server at some point. Basically, I exactly agree with the GP's use cases. ACID for things I want to keep, redis for small things that need to be fast (sessions, stats counters, etc).