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can you describe how compute scaling works? I do a lot of work in PostGIS, which can have big CPU needs depending on the function being invoked, so my workload

• kelvich 4y ago
  We are still experimenting with compute scaling, and the tech preview includes only a small fixed compute container. We have a custom proxy in front of a compute, and we can quickly change the underlying compute container with a bigger/smaller one. That works fine if you don't use per-session semantics and transactions are short-lived. But there are a lot of tradeoffs on what to do if there is a long-lived transaction or session-level object. So if we need to scale up the container in the presence of long transactions, we can: 1) roll back long transactions and enforce upscale 2) wait for a better moment to upscale (potentially forever) 3) try to do a live migration of running Postgres to another node (like VM live migrations, or CRIU-like process migration) and preserve long-running transaction So far, we plan to start with some combination of 1+2 -- should be fine for web/OLTP kind of load. But ultimately, we want to arrive at 3), but that approach has way more technical risks.