Flow: Actor-based language for C++, used by FoundationDB
13 comments
·December 8, 2025websiteapi
I'm always hearing about FoundationDB but not much about who uses it. I know Deno and obviously Apple is using it. Who else? I'd love to hear some stories about it.
CharlesW
Snowflake uses it: https://www.snowflake.com/en/blog/how-foundationdb-powers-sn...
Tigris uses it: https://www.tigrisdata.com/blog/building-a-database-using-fo...
A good collection of papers, blog posts, talks, etc.: https://github.com/FoundationDB/awesome-foundationdb
quettabit
At s2.dev (a serverless datastore for real-time streaming data), we started with DynamoDB for our metadata store, but our access patterns kept running into per-partition throughput limits. We switched to FoundationDB, and it’s been great so far.
dpedu
My company (Matterport, YC Winter '12) uses it to store metadata about 3d models. I really don't have that much to say about it because it's not my primary area of focus, and besides that, has been extremely reliable and hands-off, administration-wise. I particularly love that you can change redundancy modes on the fly, for example those listed here[1], and FDB will automatically re-arrange data to your liking, all without downtime. It handles offline/missing or replacing nodes quite well, and I credit my coworker's great efforts to make it work on top of Kubernetes for making our lives so much easier.
1: https://apple.github.io/foundationdb/configuration.html#choo...
adobrawy
Snowflake uses it as primary database for their metadata. https://www.snowflake.com/en/blog/how-foundationdb-powers-sn...
nish__
Apple uses it for iMessage I believe.
pmarreck
how does this compare to the inbox and supervisor model of erlang/elixir?
yetihehe
It doesn't. It's "promise" based, not "communicating sequential processes". Erlang has more preemptive scheduling, a "thread" can be preempted at any time, here you can only be synchronized when you wait for result. It is called "actor-based", because only functions tagged as "actor" can call waiting functions.
This is more node.js-like communication than erlang.
hawk_
Ok a related note, how does it compare to SeaStar?
thisisauserid
How did they come up with such an original and unique name? Apple does it again.
Type-safe message-passing is such a wonderful programming paradigm - and not just for distributed applications. I remember using QNX back in the 1990s. One of its fabulous features was a C message passing library allowing you to send arbitrary binary structs from one process to another. In the context of realtime software development, you often find yourself having one process that watches for events from a certain device, modify the information somehow, and then pass it on to another process that ends up doing something else. The message-passing idiom was far superior to what was available in Linux at the time (pipes and whatnot) because you were able to work with C structs. It was not strictly type safe (as is the case with FoundationDB’s library), but for the 1990s it was pretty great.