As I understand it, Sorted Sets are an in-memory feature.
Discords architecture is one where an entire guild stays on one machine. And the sorted set is part of a guild as well.
So, there is no need to persist it, since it is ephemeral in nature.
Edit: perhaps to expand on this a bit more, keep in mind that discord is not a cloud native application. They have a few strong server nodes and a Cassandra cluster (at this point I am curious if they switched to scylladb) that handle all or at least most of their client facing features.
Since they do not need to scale services, the servers they have are stateful. Hence, if the guild server crashes, so will the data structure, since the data structure is of no use if the server crashes and would need to be rebuilt from scratch either way.
(Disclaimer: I am not an insider, just an Elixir fanboy)
Discords architecture is one where an entire guild stays on one machine. And the sorted set is part of a guild as well.
So, there is no need to persist it, since it is ephemeral in nature.
Edit: perhaps to expand on this a bit more, keep in mind that discord is not a cloud native application. They have a few strong server nodes and a Cassandra cluster (at this point I am curious if they switched to scylladb) that handle all or at least most of their client facing features.
Since they do not need to scale services, the servers they have are stateful. Hence, if the guild server crashes, so will the data structure, since the data structure is of no use if the server crashes and would need to be rebuilt from scratch either way.
(Disclaimer: I am not an insider, just an Elixir fanboy)