[saghm]

It sounds like the rationale is that existing database technology is already written in it, and they want to re-use some of it. That's reasonable, but I do think that it only makes sense with the assumption that the flaws in C++ aren't large enough to be worth using something else, at which point there isn't really much need to justify using C++ at all. If someone is concerned about the flaws in C++, the benefit of relying on existing C++ libraries isn't going to seem as compelling to them for the exact same reasons they don't want to use C++ for their own code.

At the end of the day, the choice seems to be a bit circular; if you don't have concerns about C++, you'll find plenty of reasons to use it, and the arguments against it aren't going to be compelling. If you have concerns about it, the reasons to use it won't be compelling, and you'll likely agree with the arguments against it. I have to imagine that whether someone agrees with this choice will be entirely consistent with their existing opinions of C++; it doesn't seem like there are any new arguments left to make on this topic, so debates on the topic will inevitably rehash existing arguments (regardless of which side they come from) and only appeal to the people who already have formed their opinions based on finding those arguments compelling to begin with.

[wavemode]

I don't think it's quite as circular as you're making it sound. If someone has a prior contraint of needing to move quickly (which is common in startups) it can make sense to choose any arbitrary technology, if it allows them to do so. I don't think someone developing a new game in C++ necessarily has no concerns about C++, that's just the language that all the console SDKs use. I don't think someone doing data science in Python necessarily likes Python, that's just the language that most models and libraries use (and that person probably has a deadline to publish a paper!)

Another factor to consider is that, if one is indeed trying to reuse code from existing databases (regardless of the reason for doing so), code from projects like Sqlite and FoundationDB is simply far less likely to contain serious bugs than any newer Rust-based option. There are way more mistakes one can make when writing a database than just memory safety mistakes, and the mistakes tend to be extremely subtle. Code having been run in production for long periods of time under significant amounts of load is basically a fundamental prerequisite for it to make any sense to trust the data of your users to it.