Readit Newslosfair commented on Deno KV internals: building a database for the modern web deno.com/blog/building-de... · Posted by u/avinassh
Why not funnel all writes to a single region and leverage simpler transaction semantics.
Distributed consensus + fsync() determines the lower bound on commit latency. We have to wait for the data to be durable on a quorum of transaction logs before returning success for a transaction. That's usually 5-10ms, even within a single region.
losfair commented on Deno KV internals: building a database for the modern web deno.com/blog/building-de... · Posted by u/avinassh
This feels like an unnecessary layer on top? Increments can just be a function that uses an existing txn to read, incr, write. It feels like they implemented transactions on top of transactions, adding complexity?
Maybe I didn't read it right though
(I work on Deno KV)
A read-modify-write retry loop causes a high number of commit conflicts, e.g. for atomic increments on integers. Getting higher than 1/RTT per-key throughput requires the "backend" to understand the semantics of the operations - apply a function to the current value, instead of just checking whether timestamp(value) < timestamp(txn.start) and aborting commit if not.
I wonder if the expansion of process isolation tooling will ever lead us back to this situation again, anyone know? It seems to me that strict isolation would be a vital rudimentary requirement for cryofreezing processes...