Hi Andrey-san, all, From: Andrey V. Lepikhov <a.lepik...@postgrespro.ru> > On 7/27/20 11:22 AM, tsunakawa.ta...@fujitsu.com wrote: > > Could you take a look at this patent? I'm afraid this is the Clock-SI for > > MVCC. > Microsoft holds this until 2031. I couldn't find this with the keyword > "Clock-SI."" > > > > > > US8356007B2 - Distributed transaction management for database systems > with multiversioning - Google Patents > > https://patents.google.com/patent/US8356007 > > > > > > If it is, can we circumvent this patent?
> I haven't seen this patent before. This should be carefully studied. I contacted 6 people individually, 3 holders of the patent and different 3 authors of the Clock-SI paper. I got replies from two people. (It's a regret I couldn't get a reply from the main author of Clock-SI paper.) [Reply from the patent holder Per-Ake Larson] -------------------------------------------------- Thanks for your interest in my patent. The answer to your question is: No, Clock-SI is not based on the patent - it was an entirely independent development. The two approaches are similar in the sense that there is no global clock, the commit time of a distributed transaction is the same in every partition where it modified data, and a transaction gets it snapshot timestamp from a local clock. The difference is whether a distributed transaction gets its commit timestamp before or after the prepare phase in 2PC. Hope this helpful. Best regards, Per-Ake -------------------------------------------------- [Reply from the Clock-SI author Willy Zwaenepoel] -------------------------------------------------- Thank you for your kind words about our work. I was unaware of this patent at the time I wrote the paper. The two came out more or less at the same time. I am not a lawyer, so I cannot tell you if something based on Clock-SI would infringe on the Microsoft patent. The main distinction to me seems to be that Clock-SI is based on physical clocks, while the Microsoft patent talks about logical clocks, but again I am not a lawyer. Best regards, Willy. -------------------------------------------------- Does this make sense from your viewpoint, and can we think that we can use Clock-SI without infrindging on the patent? According to the patent holder, the difference between Clock-SI and the patent seems to be fewer than the similarities. Regards Takayuki Tsunakawa
