Re:Why PostgreSQL High Availability Matters and How to Achie...
by azurelake on Wednesday June 14, 2023 @08:14PM
(#36334738)
There is synchronous acknowledgement. Spanner uses 2PC + paxos groups.
If there was a bug in TrueTime, you would susceptible to phantoms, which isn’t great but almost certainly not catastrophic.
I believe that’s the only isolation issue you’d hit, since spanner locks the rows involved in a transaction.
Re:Why PostgreSQL High Availability Matters and How to Achie...
by roncesvalles on Thursday June 15, 2023 @12:43AM
(#36336478)
Spanner offers both linearizability and serializability. They use the non-standard term "external consistency" to describe the union of those two properties.
>Doesn't spanner introduce new (very unlikely) failure modes that other databases are not impacted by?
Curious if you could go into that.
Doesn't spanner introduce new (very unlikely) failure modes that other databases are not impacted by? The reliance on an external consistency model feels to me like a complete outsourcing of liability that warrants thorough investigation.
Hypothetically, if GPS went down for a prolonged period and/or a bug was found in the TrueTime system, what would happen to the consistency model around Spanner?
I feel like some applications and customers would much rather wait for a synchronous acknowledgement from the actual, live system. An extra 150ms when you are confirming a 6-figure wire transfer could easily be framed as a good thing in most circles.