On 2026-05-30, the Mastodon server I run started getting a flood of implausible signup requests. We think these are likely bots because our server rules and signup form clearly tell users to talk about their interest in gay leather. Most people sign up with something like “42 yo levis enthusiast into piss” or “Hi! I’m…
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I’ve been discussing Jepsen and partition tolerance with Peter Bailis over the past few weeks, and I’m honored to present this post as a collaboration between the two of us. We’d also like to extend our sincere appreciation to everyone who contributed their research and experience to this piece.
In the previous Jepsen analysis of RethinkDB , we tested single-document reads, writes, and conditional writes, under network partitions and process pauses. RethinkDB did not exhibit any nonlinearizable histories in those tests. However, testing with more aggressive failure modes, on both 2.1.5 and 2.2.3, has…
In a recent blog post , antirez detailed a new operation in Redis: WAIT . WAIT is proposed as an enhancement to Redis’ replication protocol to reduce the window of data loss in replicated Redis systems; clients can block awaiting acknowledgement of a write to a given number of nodes (or time out if the given threshold…
If you want to get a job as a software witch, you’re going to have to pass a whiteboard interview. We all do them, as engineers–often as a part of our morning ritual, along with arranging a beautiful grid of xterms across the astral plane, and compulsively running ls in every nearby directory–just in case things have…
This is a long article, so I've broken it up into a series of posts, listed below. You can also read the full work as a PDF or EPUB .
Previously in Jepsen , we discussed Riak . Now we’ll review and integrate our findings.
Some folks have asked whether Cassandra or Riak in last-write-wins mode are monotonically consistent, or whether they can guarantee read-your-writes, and so on. This is a fascinating question, and leads to all sorts of interesting properties about clocks and causality.
In the last Jepsen analysis, we saw that RethinkDB 2.2.3 could encounter spectacular failure modes due to cluster reconfiguration during a partition. In this analysis, we’ll talk about Crate, and find out just how many versions a row’s version identifies.
In Chapter 1 , I asserted that the grammar of Lisp is uniform: every expression is a list, beginning with a verb, and followed by some arguments. Evaluation proceeds from left to right, and every element of the list must be evaluated before evaluating the list itself. Yet we just saw, at the end of Sequences , an…
Last weekend I was trying to pull together sources for an essay and kept finding “fact check” pages from factually.co . For instance, a Kagi search for “pepper ball Chicago pastor” returned this Factually article as the second result:
I write a lot of reductions: loops that combine every element from a collection in some way. For example, summing a vector of integers:
We’ve learned the basics of Clojure’s syntax and evaluation model . Now we’ll take a tour of the basic nouns in the language.
Percona’s CTO Vadim Tkachenko wrote a response to my Galera Snapshot Isolation post last week. I think Tkachenko may have misunderstood some of my results, and I’d like to clear those up now. I’ve ported the MariaDB tests to Percona XtraDB Cluster, and would like to confirm that using exclusive write locks on all…
Previously in Jepsen , we discussed Redis . In this post, we’ll see MongoDB drop a phenomenal amount of data. See also: followup analyses of 2.6.7 and 3.4.0-rc3 .
Update, November 2023: here are the full term rewrite and language macros which formed the seed of this story. These files include OO notation as well as the basic Algol syntax shown here. There is also a sketch of an object-oriented language with classes and inheritance, implemented as a Clojure macro. I do not…
This article is part of Jepsen , a series on network partitions. We’re going to learn about distributed consensus, discuss the CAP theorem’s implications, and demonstrate how different databases behave under partition.
Previously on Jepsen , we introduced the problem of network partitions . Here, we demonstrate that a few transactions which “fail” during the start of a partition may have actually succeeded.
Previously on Jepsen , we explored two-phase commit in Postgres . In this post, we demonstrate Redis losing 56% of writes during a partition.
Previously in Jepsen , we discussed Redis . In this post, we’ll see MongoDB drop a phenomenal amount of data. See also: followup analyses of 2.6.7 and 3.4.0-rc3 .