Comment by halfcat
1 month ago
That’s my intuition as well, but it does raise a question in my mind.
We have storage solutions that are far more robust than the individual hard drives that they’re built upon.
One example that comes to mind is Microsoft Exchange databases. Traditionally these were run on servers that had redundant storage (RAID), and at some point Microsoft said you could run it without RAID, and let their Database Availability Groups handle the redundancy.
With Postgres that would look like, say, during an HTTP request, you write the change to multiple Postgres instances, before acknowledging the update to the requesting client.
Yes exactly! That's how Postgres synchronous replication works. If you turn on synchronous replication, then you won't lose data unless all your replicas are wiped out. The question the original poster was asking was what guarantees can be provided if you DON'T use synchronous replication--and the answer is that there's no such thing as a free lunch.