Editing Vector clock (section)

==Other mechanisms==
{{Incomplete list|date=June 2023}}

* In 1999, Torres-Rojas and Ahamad developed '''Plausible Clocks''',<ref>{{Citation |author1=Francisco Torres-Rojas |author2=Mustaque Ahamad
|title=Plausible clocks: constant size logical clocks for distributed systems |journal=Distributed Computing |volume=12 |issue=4 |year=1999 |pages=179–195 |doi=10.1007/s004460050065 |s2cid=2936350
|url=https://www.cc.gatech.edu/fac/Mustaque.Ahamad/pubs/plausible.ps|url-access=subscription }}</ref> a mechanism that takes less space than vector clocks but that, in some cases, will totally order events that are causally concurrent.

* In 2005, Agarwal and Garg created '''Chain Clocks''',<ref>{{cite book |last1=Agarwal |first1=Anurag |last2=Garg |first2=Vijay K. |title=Proceedings of the twenty-fourth annual ACM symposium on Principles of distributed computing |chapter=Efficient dependency tracking for relevant events in shared-memory systems |date=17 July 2005 |pages=19–28 |doi=10.1145/1073814.1073818 |chapter-url=http://users.ece.utexas.edu/~garg/dist/agarwal-garg-DC.pdf |access-date=21 April 2021 |publisher=Association for Computing Machinery|isbn=1-58113-994-2 |s2cid=11779779 }}</ref> a system that tracks dependencies using vectors with size smaller than the number of processes and that adapts automatically to systems with dynamic number of processes.
* In 2008, Almeida ''et al.'' introduced '''Interval Tree Clocks'''.<ref>{{Citation |
last1=Almeida | first1=Paulo | last2=Baquero | first2=Carlos | last3=Fonte | first3=Victor |
contribution=Interval Tree Clocks: A Logical Clock for Dynamic Systems |
title=Principles of Distributed Systems |
volume=5401 |
publisher=Springer-Verlag, Lecture Notes in Computer Science |
year=2008 | doi=10.1007/978-3-540-92221-6 |
url=http://gsd.di.uminho.pt/members/cbm/ps/itc2008.pdf |
pages=259–274 |
series=Lecture Notes in Computer Science | bibcode=2008LNCS.5401.....B |
editor1-last=Baker |
editor1-first=Theodore P. |
editor2-last=Bui |
editor2-first=Alain |
editor3-last=Tixeuil |
editor3-first=Sébastien |
isbn=978-3-540-92220-9 }}</ref><ref>{{Citation | last1=Almeida | first1=Paulo | last2=Baquero | first2=Carlos | last3=Fonte | first3=Victor | title=Interval Tree Clocks: A Logical Clock for Dynamic Systems | volume=5401 | pages=259 | contribution=Interval Tree Clocks: A Logical Clock for Dynamic Systems | year=2008 | doi=10.1007/978-3-540-92221-6_18 | url=https://www.researchgate.net/publication/235246938 | series=Lecture Notes in Computer Science | isbn=978-3-540-92220-9 | hdl=1822/37748 | hdl-access=free }}</ref><ref>{{Citation | last1=Zhang | first1=Yi | title=Background Preliminaries: Interval Tree Clock Results | contribution=Background Preliminaries: Interval Tree Clock Results | year=2014 | url=https://cs.uwaterloo.ca/~mkarsten/cs755-F14/presentations/ITC.pdf }}</ref> This mechanism generalizes Vector Clocks and allows operation in dynamic environments when the identities and number of processes in the computation is not known in advance.

* In 2019, Lum Ramabaja proposed '''Bloom Clocks''', a probabilistic data structure based on [[Bloom filters]].<ref>{{cite journal |last1=Pozzetti |first1=Tommaso |last2=Kshemkalyani |first2=Ajay D. |title=Resettable Encoded Vector Clock for Causality Analysis With an Application to Dynamic Race Detection |journal=IEEE Transactions on Parallel and Distributed Systems |date=1 April 2021 |volume=32 |issue=4 |pages=772–785 |doi=10.1109/TPDS.2020.3032293|s2cid=220362525 |doi-access=free }}</ref><ref>{{Citation |author1=Lum Ramabaja |title=The Bloom Clock |year=2019 |arxiv=1905.13064 |bibcode=2019arXiv190513064R }}</ref><ref>{{cite book |last1=Kulkarni |first1=Sandeep S |last2=Appleton |first2=Gabe |last3=Nguyen |first3=Duong |title=Proceedings of the 23rd International Conference on Distributed Computing and Networking |chapter=Achieving Causality with Physical Clocks |date=4 January 2022 |pages=97–106 |doi=10.1145/3491003.3491009|arxiv=2104.15099 |isbn=9781450395601 |s2cid=233476293 }}</ref> Compared to a vector clock, the space used per node is fixed and does not depend on the number of nodes in a system. Comparing two clocks either produces a true negative (the clocks are not comparable), or else a suggestion that one clock precedes the other, with the possibility of a false positive where the two clocks are unrelated. The false positive rate decreases as more storage is allowed.