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When I started the Redis project more than ten years ago I was in one of the most exciting moments of my career. My co-founder and I had successfully launched two of the major web 2.0 services of the Italian web. In order to make them scalable we had to invent many new concepts, that were already known in the field most of the times, but we didn’t know, nor we cared to check. Problem? Let’s figure

antirez 1723 days ago. 187241 views. Finally Redis 6.0.0 stable is out. This time it was a relatively short cycle between the release of the first release candidate and the final release of a stable version. It took about four months, that is not a small amount of time, but is not a lot compared to our past records :) So the big news are the ones announced before, but with some notable changes. Th

[Note: this post no longer describes the client side implementation in the final implementation of Redis 6, that changed significantly, see https://redis.io/topics/client-side-caching] The New York Redis day was over, I get up at the hotel at 5:30, still pretty in sync with the Italian time zone and immediately went walking on the streets of Manhattan, completely in love with the landscape and the

Martin Kleppmann, a distributed systems researcher, yesterday published an analysis of Redlock (http://redis.io/topics/distlock), that you can find here: http://martin.kleppmann.com/2016/02/08/how-to-do-distributed-locking.html Redlock is a client side distributed locking algorithm I designed to be used with Redis, but the algorithm orchestrates, client side, a set of nodes that implement a data s

Months ago the maintainer of an OSS project in the sphere of system software, with quite a big and active community, wrote me an email saying that he struggles to continue maintaining his project after so many years, because of how much psychologically taxing such effort is. He was looking for advices from me, I’m not sure to be in the position of giving advices, however I told him I would write a

Yesterday a concerned Redis user wrote the following on Hacker News: — https://news.ycombinator.com/item?id=19204436 — I love Redis, but I'm a bit skeptical of some of the changes that are currently in development. The respv3 protocol has some features that, while they sound neat, also could significantly complicate client library code. There's also a lot of work going into a granular acl. I can't

For quite some time I’ve wanted to record a new video talking about code comments for my "writing system software" series on YouTube. However, after giving it some thought, I realized that the topic was better suited for a blog post, so here we are. In this post I analyze Redis comments, trying to categorize them. Along the way I try to show why, in my opinion, writing comments is of paramount imp

Today a page about the new Common Clause license in the Redis Labs web site was interpreted as if Redis itself switched license. This is not the case, Redis is, and will remain, BSD licensed. However in the era of [edit] uncontrollable spreading of information, my attempts to provide the correct information failed, and I’m still seeing everywhere “Redis is no longer open source”. The reality is th

A bit more than one month ago I received an email from the Apple Information Security team. During an auditing the Apple team found a security issue in the Redis Lua subsystem, specifically in the cmsgpack library. The library is not part of Lua itself, it is an implementation of MessagePack I wrote myself. In the course of merging a pull request improving the feature set, a security issue was add

In a great series of articles Kyle Kingsbury, aka @aphyr on Twitter, attacked a number of data stores: [1] http://aphyr.com/tags/jepsen Postgress, Redis Sentinel, MongoDB, and Riak are audited to find what happens during network partitions and how these systems can provide the claimed guarantees. Redis is attacked here: http://aphyr.com/posts/283-call-me-maybe-redis I said that Kyle "attacked" the

Redis is often used for caching, in a setup where a fixed maximum memory to use is specified. When new data arrives, we need to make space by removing old data. The efficiency of Redis as a cache is related to how good decisions it makes about what data to evict: deleting data that is going to be needed soon is a poor strategy, while deleting data that is unlikely to be requested again is a good o

Until a few months ago, for me streams were no more than an interesting and relatively straightforward concept in the context of messaging. After Kafka popularized the concept, I mostly investigated their usefulness in the case of Disque, a message queue that is now headed to be translated into a Redis 4.2 module. Later I decided that Disque was all about AP messaging, which is, fault tolerance an

A 10x programmer is, in the mythology of programming, a programmer that can do ten times the work of another normal programmer, where for normal programmer we can imagine one good at doing its work, but without the magical abilities of the 10x programmer. Actually to better characterize the “normal programmer” it is better to say that it represents the one having the average programming output, am

It’s not yet stable but it’s soon to become, and comes with a long list of things that will make Redis more useful for we users: finally Redis 4.0 Release Candidate 1 is here, and is bold enough to call itself 4.0 instead of 3.4. For me semantic versioning is not a thing, what I like instead is try to communicate, using version numbers and jumps, what’s up with the new version, and in this specifi

WARNING: Long pretty useless blog post. TLDR is that I wrote, just for fun, a text editor in less than 1000 lines of code that does not depend on ncurses and has support for syntax highlight and search feature. The code is here: http://github.com/antirez/kilo. Screencast here: https://asciinema.org/a/90r2i9bq8po03nazhqtsifksb For the sentimentalists, keep reading… A couple weeks ago there was this

It was a matter of time but it eventually happened. In the Redis 1.0 release notes, 7 years ago, I mentioned that one of the interesting features for the future was “loadable modules”. I was really interested in such a feature back then, but over the years I became more and more skeptic about the idea of adding loadable modules in Redis. And probably for good reasons. Modules can be the most inter

It took more than expected, but finally we have it, Redis 3.2.0 stable is out with changes that may be useful to a big number of Redis users. At this point I covered the changes multiple time, but the big ones are: * The GEO API. Index whatever you want by latitude and longitude, and query by radius, with the same speed and easy of use of the other Redis data structures. Here you can find the API

Today I’m happy to announce that the first release candidate for Disque 1.0 is available. If you don't know what Disque is, the best starting point is to read the README in the Github project page at http://github.com/antirez/disque. Disque is a just piece of software, so it has a material value which can be zero or more, depending on its ability to make useful things for people using it. But for

IMPORTANT EDIT: Redis 3.2 security improved by implementing protected mode. You can find the details about it here: https://www.reddit.com/r/redis/comments/3zv85m/new_security_feature_redis_protected_mode/ From time to time I get security reports about Redis. It’s good to get reports, but it’s odd that what I get is usually about things like Lua sandbox escaping, insecure temporary file creation,

If you know me, you know I’m not the kind of guy that considers competing products a bad thing. I actually love the users to have choices, so I rarely do anything like comparing Redis with other technologies. However it is also true that in order to pick the right solution users must be correctly informed. This post was triggered by reading a blog post published by Mike Perham, that you may know a

Everybody knows Redis is single threaded. The best informed ones will tell you that, actually, Redis is *kinda* single threaded, since there are threads in order to perform certain slow operations on disk. So far threaded operations were so focused on I/O that our small library to perform asynchronous tasks on a different thread was called bio.c: Background I/O, basically. However some time ago I

I consider myself very lucky for contributing to the open source. For me OSS software is not just a license: it means transparency in the development process, choices that are only taken in order to improve software from the point of view of the users, documentation that attempts to cover everything, and simple, understandable systems. The Redis community had the privilege of finding in Pivotal, a

Nor subjects, for what matters. Everybody will tell you to don't add a dot at the end of the first line of a commit message. I followed the advice for some time, but I'll stop today, because I don't believe commit messages are titles or subjects. They are synopsis of the meaning of the change operated by the commit, so they are small sentences. The sentence can be later augmented with more details

I’m back from Paris, DotScale 2015 was a very interesting conference. Before leaving I was working on Sentinel in the context of the unstable branch: the work was mainly about connection sharing. In short, it is the ability of a few Sentinels to scale, monitoring many masters. Before to leave, and now that I’m back, I tried to “secure” a set of features that will be the basis for Redis 3.2. In the

EDIT: In case you missed it, Disque source code is now available at http://github.com/antirez/disque It is a few months that I spend ~ 15-20% of my time, mostly hours stolen to nights and weekends, working to a new system. It’s a message broker and it’s called Disque. I’ve an implementation of 80% of what was in the original specification, but still I don’t feel like it’s ready to be released. Sin

Redis speed could be one selling point for new users, so following the trend of comparative “advertising” it should be logical to have a few comparisons at Redis.io. However there are two problems with this. One is of goals: I don’t want to convince developers to adopt Redis, we just do our best in order to provide a suitable product, and we are happy if people can get work done with it, that’s wh

Today I was testing Redis latency using m3.medium EC2 instances. I was able to replicate the usual latency spikes during BGSAVE, when the process forks, and the child starts saving the dataset on disk. However something was not as expected. The spike did not happened because of disk I/O, nor during the fork() call itself. The test was performed with a 1GB of data in memory, with 150k writes per se