[HN Gopher] Who Invented Vector Clocks? ___________________________________________________________________ Who Invented Vector Clocks? Author : rntz Score : 35 points Date : 2023-04-09 20:35 UTC (2 hours ago) (HTM) web link (decomposition.al) (TXT) w3m dump (decomposition.al) | ChuckMcM wrote: | Vector clocks are pretty neat. I didn't invent them but I used a | crude approximation when I was designing what was to become NIS+ | at Sun Microsystems. | | Given the problem that you want to accept updates to a database | at multiple servers but cannot guarantee that all of those | servers have the same notion of time and thus creating an | accurate mutation vector that leaves the state of the database | consistent, NIS+ used a tuple of (update, secondary-server-time) | which the primary could query the secondary and compute a time | delta (positive or negative) that would allow it to sort updates | to the same database entry from multiple secondaries into a | primary relative time order. It could then apply the updates and | produce deltas for all secondaries which would apply any | necessary changes to their database. | | As a systems problem I really enjoyed the challenge. | hinkley wrote: | > The idea of vector timestamps was developed independently by | Ladin and Liskov [LL86]. | | A few years ago when I ended up down the rabbit hole on CRDTs and | alternatives I learned of Liskov's work on time vectors, which is | still my top "things you didn't know about Barbara Liskov" fact. | infogulch wrote: | It depends on your reference frame... | topaz0 wrote: | Unlikely: assuming all of the authors of the various papers | were on earth at the time, the spacetime intervals separating | their discoveries were almost certainly timelike, in which case | there is no ambiguity in their ordering. Unless they were | within a few ms of each other (in the earth's reference frame). | gwern wrote: | This is a good example of how academic citation practices subtly | launder out the role of compute, trial-and-error, and | practitioners in favor of academia. OP concludes that if you want | to cite Fidge & Mattern for credit for 'developing the _theory_ | ', that's fine. But notice, that's not how it started and is an | answer to a different - no one was asking, 'who finally explained | why vector clocks work in a rigorous way', the very title is 'who | _invented_ vector clocks ' (repeated in the first sentence, and | in various forms thereafter as 'system...developed', | 'introduced', 'idea...developed', etc), and she objects to WP | describing her as uncovering who really 'invented' vector clocks. | The actual answer to her question would seem to be Parker 1983. | (And looking at the description of 'LOCUS' in | https://pages.cs.wisc.edu/~remzi/Classes/739/Papers/parker83... , | it sounds more like they are reverse-engineering why LOCUS | works...) | sublinear wrote: | > So, the current version of the Wikipedia page on vector clocks | is wrong, or at least misleading, about the origin of the idea, | and it's kind of my fault. | | No. 0% fault of the author and 100% the fault of the Wikipedia | editor. Generally speaking, people who are unwilling to ensure | the accuracy of their work don't deserve the privilege to do that | work. | threatofrain wrote: | > Generally speaking, people who are unwilling to ensure the | accuracy of their work don't deserve the privilege to do that | work. | | This is all volunteer labor. Anyone can be a volunteer if | they'd like. Wikipedia encourages mistakes (or "boldness") and | assumes that due to a network of volunteers and the density of | interest, an article will eventually become better. | | Programming docs in open source often have errors. Do the | volunteers not deserve the "privilege" of offering their time | for free? | gslin wrote: | It's interesting to see someone trying to decide the invention | clock in the real world... ___________________________________________________________________ (page generated 2023-04-09 23:00 UTC)