> I just keep everything in memory in native data structures and flush to disk periodically;
Can you expand on what you mean by this? I am interpreting that to mean that you are actually writing to a file and reading from a file rather than using SQL?
They're storing their data in native Rust objects and read or write them in server application RAM. In case data becomes larger than available RAM, they have set up a large swap, which is a file or a disk partition that the OS uses when no more real RAM is available, while acting like nothing is happening (and everything gets 1000x slower). They periodically serialize these in-memory objects to a file on disk, and presumably (they didn't specify, but I feel it's implied) they're reading this file and deserialize it during initialization/startup phase.
