Keyboard shortcuts

/ or ⌘/Ctrl K
Find a note
j / k
Next / previous section or linked note
h / l
Collapse or go to parent / expand or enter
e or Alt-click
Read a linked note here
o
Open focused note on its own
g g / G
First / last section or linked note
g h / g a
Home / all notes
g b / g t
Backlinks / table of contents
t
Cycle System, Light, Dark
? / Esc
Show / close this reference

Search: ↑/↓ or Ctrl N/P, Enter to open. Shortcuts pause while typing.

truetime [1e49e40d]

Tags: clocks (distributed systems), cloud

https://cloud.google.com/spanner/docs/true-time-external-consistency

  • HA distributed clock service, similar to NTP

  • True time provides an interval of time, and a way to tell if things were bfeore and after

    • TT.now() -> TTinterval: [earliest, latest]
    • TT.after(t) -> True if t has definitely passed
    • TT.before(t) -> True if t has definitely not arrived

  • TrueTime error comes from round trip time to the clock server, clock drift, and time to sycnronize wit hother clocks

    file:2024-02-26_19-38-46_screenshot.png

  • truetime effectively allows us to do what vector clocks do but with much less space
  • Gives Spanner it's external consistency (linearizability).