Patterns of Distributed Systems

Problem

When Lamport Clock is used as a version in Versioned Value, clients do not know the actual date-time when the particular versions are stored. It’s more convenient for clients to access versions using date and time like 01–01–2020 instead of an integer like 1, 2, 3.

Solution

Hybrid logical clock [Demirbas2014] provides a way to have a version which is monotonically increasing just like a simple integer, but also has relation to the actual date and time. Hybrid clocks are used in practice by databases like MongoDB⁷⁷ or CockroachDB.⁷⁸

77. https://www.mongodb.com/blog/post/transactions-background-part-4-the-global-logical-clock ...