PTP/TrueTime vs. HLC when it comes to snapshots

By Lu Pan in clock on

Google's Spanner paper was published in 2012 which famously introduced the TrueTime API. PTP is the standard equivalent of TrueTime. Two years later, Kulkarni, et al. published the Hybrid Logical Clock paper – Logical Physical Clocks and Consistent Snapshots in Globally Distributed Databases. In the HLC paper, they list the downsides…

API for Assigning Timestamp

By Lu Pan in clock on

This is a follow-up post of my previous one [https://blog.the-pans.com/notes-on-the-spanner/] about Spanner. There I talked about how Spanner uses TrueTime API to achieve external consistency at global scale and hide sharding and replication from users. In this post, I want to discuss different options of assigning…