CockroachDB's Consistency Model
The suggestion that this anomaly  can occur in FaunaDB is wrong:<p><pre><code>  &gt; We do not allow the bad outcome in the Hacker News commenting scenario. Other 
  &gt; distributed databases that claim serializability do allow this to happen.
</code></pre>
FaunaDB&#x27;s consistency levels are as follows:<p><pre><code>             | No indices   | Serializable indices | Other indices
  -----------+--------------+----------------------+--------------
  Read-Write | Strict-1SR   | Strict-1SR           | Snapshot
  Read-Only  | Serializable | Serializable         | Snapshot
</code></pre>
In FaunaDB, all read-write transactions execute at external consistency, including all their row read intents, and all index intents when requested. Any read-only transaction, even if uncoordinated, will see a consistent prefix view of all its priors. Not just causal priors, so there is no &quot;causal reversal&quot;. All physical, linearizable, multi-partition priors.<p>In FaunaDB, it is not possible to see the later comment without seeing the previous comment, even when executing at snapshot instead of externally consistent isolation.<p>FaunaDB can serve serializable&#x2F;snapshot reads out of any datacenter without any global coordination, and can serve externally consistent reads with coordination whenever requested. CockroachDB doesn&#x27;t offer global reads at all, to work around the clock skew issues, but can only serve reads from partition leaders.<p>Comparing these models fairly requires executing all transactions in FaunaDB at external consistency, which is both more consistent, and has lower tail latency in a global context, than CockroachDB.