[Tech] Separation of Storage and Compute (Databases) - Nikita Shamgunov

<p>Listen to the Changelog: https://changelog.com/podcast/510</p><p><strong>Transcript</strong></p><p>So elastic compute makes sense, and scaling down because you have like ephemeral on-demand resource usage, right? Like, all of a sudden, I have to answer a bunch of HTTP requests, and so my server has to do stuff, and then everybody leaves, and my website doesn’t get any hits, and I could scale that down. With databases, if I’ve got a one-gigabyte database, it’s just like, it’s always there. I mean, all that data is there, and I could access any part of it at any time, or I need to… And we don’t know which parts. So I have a hard time with database scaling to zero, unless you’re – I don’t know, just like stomaching the cost… Or tell us how that works with Neon. Are you just stomaching the costs of keeping that online, or are you actually scaling it down?</p><p><a href="https://changelog.com/podcast/510#transcript-15"><strong>NIKITA SHAMGUNOV</strong></a></p><p>We’re actually scaling that down. Let me explain how this works, and it may get quite technical. The first thing is what should be the enabling technology of scaling that down? If you’re just kind of thinking, “How would I build serverless Postgres?” and if you ask a person that is not familiar with database internals, they would say something like, “Well, I would put it in the VM maybe, or I would put it in the container, I would put that stuff into Kubernetes… Maybe I can change the size of the containers…” The issue with all that, as you start moving those containers around, it will start breaking connections, because databases like to have a persistent connection to them. And then you will be impacting your cache. Databases like to have a working set in memory, and if you don’t have a working set of memory, you’re paying the performance hit by bringing that data from cold storage to memory.</p><p>The third thing that you will find out, that if the database is large enough, it’s really, really hard to move database from host to host, because tha